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Introduction to Positive Psychology: Happiness and the Science of Pleasure.

Table of Contents


As the Roman Emperor, Marcus Aurelius said, “Life is but what we deem it.”1

You may find the following aphorism useful: Choose good goals then enjoy the journey by living in the moment, mindful and aware.

Evidence and Examples


Mindful practice, such as mindful meditation, means paying attention to cultivate unbiased awareness moment-to-moment.

Evidence shows the following benefits of mindful meditation: greater attention, better awareness, increased memory, more positive emotions, improved self control, better relationships, better diet, increased well-being, increased satisfaction and more relaxed. (See Dance With Mindfulness and Meditation.)

“The evidence for a positive effect of meditation on subjective well-being is becoming quite impressive.”2

Five ways to well being

This section is a direct quote from the New Economics Foundation report identifying “a set of evidence-based actions to improve well-being”.

A review of the most up-to-date evidence suggests that building the following five actions into our day-to-day lives is important for well-being:






Most People Feel Generally Happy

“When asked, most people say that they are happy or very happy, and this result is robust as regards age, place, sex, or different ways of asking the question. [With self bias] pretty much everyone claims above average levels of satisfaction with their lives.”3 (i.e. Positivity Offset)

Immediate happiness is mainly influenced by personality traits that remain stable over time. We evolved to strive. A belief that we will feel happier in the future helps keep us striving. Without intervention, you are likely to feel as happy in the future as you do now. However, we can increase our happiness to the top of our range through meditation, drugs and by consciously changing the way we view our experiences eg cognitive behavioural therapy. Humans flourish by participating in engrossing activities that take us out of ourselves, encourage us to live in the moment and connect with others and the wider world.4

Changing the Subject

Ironically focusing on one's own happiness often reduces contentment. Changing the subject and pursuing engrossing activities can produce lasting happiness. As John Stuart Mill said, “Those only are happy... who have their minds fixed on some object other than their own happiness. Aiming thus at something else, they find happiness along the way.”5

Pursue absorbing activities, enjoyable for their own sakes, such as creative projects, friendship, education, or learning to dance.

As Joseph Campbell said, “Follow your bliss.”

Strengths and Virtues

Play to your strengths. Dr Martin Seligman compiled a list of 24 signature strengths covering wisdom and knowledge, courage, humanity and love, justice, temperance, and transcendence.

Identify your signature strengths at

Signature strengths are virtues and characteristics ubiquitous across cultures that are worthwhile goals in themselves: Curiosity, Love of learning, Judgement, Ingenuity, Emotional Intelligence, Perspective, Valour, Perseverance, Integrity, Kindness, Loving, Citizenship, Fairness, Leadership, Self- control, Prudence, Humility, Appreciation, Gratitude, Hope, Spirituality, Forgiveness, Humour, and Zest.

Applying signature strengths in pursuit of your goals, for example at work, can increase happiness.6

The Difference Between Wanting and Liking

Wanting and liking are related but distinct systems. The mental mechanisms controlling “wanting” and “liking” are often linked, however they can also function as separate systems. Hence it is entirely possible to strongly desire something that actually brings very little pleasure. “This accounts for the observation that we often work hard in life for things that turn out not to increase happiness.”7

Although an oversimplification, evidence suggests a dopamine related system influences wanting and an opioid systems roughly relates to pleasure.

Evidence also suggest that another neurotransmitter called serotonin can modulate between negative emotions and positive emotions, where negative emotions represent short-term priorities like stress, fear, fight-or-flight and positive emotions represent long-term opportunities like happiness, cooperation and sociability. 8 9

Happiness improves if we desire goals that actually increase pleasure and pursue activities that are rewarding in themselves such as socialising with friends, going out, exploring, helping others, creativity, culture, meditation and dancing. Humans adapt to their environments, both good and bad, so vary your pleasures.

Pleasant Activity Training

Making a note of our activities when we feel happy is a simple way to identify which experiences bring genuine happiness. In this way, “pleasant activity training” helps identify when people feel happy and encourages them to enjoy those activities more often. This also helps to avoid pursuing empty ambitions that do not actually produce contentment. Given that people often feel strong desires for goals that do not bring lasting happiness, “pleasant activity training” can help us identify which activities bring genuine pleasure.

Typically, “pleasant activity training” highlights seeing friends, visiting new places, sport, going out and cultural activities.10

“Happiness training programmes... aim to increase positive emotion. Such increase is generally achieved by pleasant activity training. This staggeringly complex technique consists of determining which activities are pleasant, and doing them more often... Pleasant activity training is one way of reliving depression, and furthermore, when applied to non-depressed volunteers over several weeks, also improves their ratings of happiness.”11

Learning new habits or making lifestyle changes can take over three months of practice.12

Adaptation and Habituation

We acclimatise to constant conditions and only notice the new. Habituation means we adapt to almost all situations, both good and bad. Exceptions include offensive people and noise,13 and the death of a spouse or a child in road traffic accident14 but, in general, we adapt to changes in circumstances and tend to return to our normal level of happiness.

“... [A] barrier to raising your level of happiness is the “hedonic treadmill”, which causes you to rapidly and inevitably adapt to good things by taking them for granted. As you accumulate more material possessions and accomplishments, your expectations rise. The deeds and things you worked so hard for no longer make you happy; you need to get something even better to boost your level of happiness into the upper reaches of its set range. But once you get the next possession or achievement, you adapt to it as well, and so on. There is, unfortunately, a good deal of evidence for such a treadmill.”15

“... habituation, or adaptation, is an inviolable neurological fact of life... Inject into your life as many events that produce pleasure as you can, but spread them out... Try to find the optimal spacing that keeps your habituation of your pleasures at bay.”16

Change your pleasures and plan for alternative ways to pursue happiness.

Savouring Pleasures

In the chapter on “Happiness in the Present” in the book “Authentic Happiness”, Dr Martin Seligman suggests the following tips for savouring pleasures:

1. sharing with others

2. collecting memorabilia and keepsakes

3. sharpening perceptions and awareness of your senses

4. absorption and immersion in enjoyable activities

5. basking, giving thanks, marvelling and luxuriating

Note the activities that bring you genuine lasting happiness and consider how you might savour the pleasures of these enjoyable activities. Examples you might like to try include reading, soaking in bath, enjoying fine art, watching drama, laughing at comedy, eating fine food, walking, playing a game, and dancing.

Happiness and Wealth

Access to enough resources to enjoy bodily comfort brings obvious benefits. However, considering our ability to desire goals that do not necessarily result in happiness, and the fact that people quickly adapt to increases in wealth means that, above a certain level, increasing wealth does not result in a corresponding increase in happiness.


Relative wealth and opportunities can impact on our happiness. People on moderate incomes can feel sad if they compare themselves to the rich. Hence inequalities in income can decrease happiness. However, even if your income rises, there are always richer people to compare yourself with. Despite our craving for riches, increases in wealth do not generally result in lasting increases in happiness. Hence money really can't buy you happiness. Income does not equate to happiness. “If you can find alternative ways of being in control of your life, then you can be just as happy [as the wealthy] even if your income is low.”18

Count the Good Things in Life

Our thinking often leads our emotions. How we interpret ideas and events greatly influences our emotions. Regularly taking the time to consider the good in our current circumstances can increase our positive feelings.19

Context and Happiness

Our thoughts about our own well-being often require a frame of reference. People report better general life satisfaction on sunny days than on rainy days. Interestingly this effect disappears if the subject is first asked about the weather. It seems we account for biasing emotions when we become consciously aware of them. Hence, our sense of happiness depends on context.20 21

In an experiment subjects were asked to use a photocopier before being asked about their life satisfaction. The experimenters arranged for one group to find a coin on the photocopier and that group reported higher life satisfaction in general. People feel happier if they believe life is going better than expected. Hence, reported happiness depends of the subject's frame of reference.22 23 24

Happiness Hypothesis

“Happiness is not something that you can find, acquire or achieve directly. You have to get the conditions right and then wait. Some of those conditions are within you, such as coherence among the parts and levels of your personality. Other conditions require relationships to things beyond you: Just as plants need sun, water and good soil to thrive, people need love, work and a connection to something larger. It is worth striving to get the right relationships between yourself and others, between yourself and your work, and between yourself and something larger than yourself. If you get these relationships right, a sense of purpose and meaning will emerge.”25

Cognitive Behavioural Therapy (CBT)

Cognitive behavioural therapy provides the tools to challenge negative thoughts and reduce unhappiness. CBT reduces the impact of negative thoughts when “therapist and client work to identify patterns of negative thinking, and expose their irrationality.”26

Developing explanations for misfortunes that are “specific and temporary” helps challenge irrational negativity. If your current situation is negative many future situations will still be positive. For example, “I'm all washed up” becomes “I'm exhausted today”. “I can't stick to diets” can be viewed as “I find it hard sticking to diets when I eat out”. Similarly, “I'm repulsive” is replaced by “I'm repulsive to this person”.27

In his books "Learned Optimism" and “Authentic Happiness” Martin Seligman describes an ABCD method (which he and his colleagues adapted from the works of psychologists Aaron Beck and Albert Ellis) where ABCD stands for Adversity, Beliefs, Consequences, Distract and Dispute.

Identifying Adversity requires us to note which situations regularly trigger negative thoughts. Then examine which of our self Beliefs translate this adversity into negative Consequences, such as needlessly feeling sad. Improvement comes if you Distract yourself from dwelling on negative thoughts by clapping your hands, closely examining an object or telling yourself that you will think about it at some specific time in the future. Better still, Dispute your thoughts (just as you might argue against a rude rival who needlessly criticised you). Look for evidence to argue against irrational negative thoughts.28

If you find you have gratuitous negative thoughts then deliberately dispute those thoughts and argue against them. If someone else passed a harsh judgement then you might argue against that point of view, so use the same technique to argue against your own excessively negative thoughts.29

Dwelling on a negative thought yields no useful information, so distract yourself with pleasant activities. Neutral activities like work or doing chores can also distract. Alcohol and drugs fare better as celebrations than distractions. Try distracting yourself by going for a walk, taking exercise, playing sport, or dancing.


In his books "Learned Optimism" and “Authentic Happiness” Martin Seligman also describes how gaining a realistic optimism can increase feelings of well-being. As an example, rather than leaping to the worst possible conclusion upon encountering a difficult situation, rather consider both the worst and best possibilities and remind yourself that reality will likely lie somewhere between these two extremes.

As with cognitive behavioural therapy, optimism can be encouraged over time. Considering the consequences of failure can be useful for deciding when to employ positive optimism. If the consequences of failure might be catastrophic, such as pilots of surgeons, then exercise caution. If, however, the consequences of failure are trivial, such as meeting someone new at a party, then employ optimism.

Types of Happiness

In his book "Happiness: The Science Behind Your Smile", Daniel Nettle splits the broad title of Happiness into three areas:

In his book, "Authentic Happiness", Martin Seligman also identifies three types of happiness:

When engrossed by the good life and absorbed by the meaningful life, we become unselfconscious. When caught up “in the moment”, it's often in retrospect that we realise how happy we were. Mihaly Csikszentmihalyi, calls this “Flow”.


Flow: a psychological state where a person is fully immersed and focused on an activity or task.

Feeling fully immersed in an activity frequently brings a sensation of effortless attention, or “flow”. Gaining an enjoyable sense of satisfaction often involves activities that have little immediate emotional components but, over time, feel very gratifying. Challenge should be appropriate for the level of skill. Hence, to avoid anxiety, level of challenge should be tailored to suit an individual's level of skill. To avoid boredom level of challenge should increase as skills increase. See

Flow seems to require “... clear goals [for each step of an activity], immediate feedback, and a balance between opportunities for action and the individual’s ability to act.”30

Mihaly Csikszentmihalyi's book called “Flow” documents his research into human flourishing. This book investigates the philosophy and science of optimal experience. If you read this book please note Mihaly is not referring to the paranormal when using the expression “psychic energy”; he means “mental energy”.

The author introduces “Autotelic” derived from the Greek “auto” meaning self and “telikós” pertaining to an end or cause. Autotelic personalities define goals from within one's own consciousness rather than from external influences such as instinct or social conventions. Starting with the ancient Delphic aphorism, "Know yourself" and Socrates' assertion "the unexamined life is not worth living", this relates to the existentialist concept of Authentic Living where a person realises choices are free and expresses genuine thoughts and feelings with decisions based on a rational evaluation of experience. See Mihaly also suggests we can create our own meanings of life and unify our flow activities with an overarching purpose.

One of the good summarising texts in Flow comes when Mihaly quotes Bertrand Russell: “Gradually I learned to be indifferent to myself and my deficiencies; I came to centre my attention increasingly upon external objects: the state of the world, various branches of knowledge, individuals for whom I felt affection.” See

Focussing attention on the world avoids always thinking about yourself and helps us discover new solutions. Many flow activities are enjoyable for their own sake and do not demand external motivation. These flow activities feel absorbing and fun, such as hiking in hills, socialising, studying an intriguing subject, playing games or dancing.

Effortless Attention and Ballroom Dancing

"Everyone has experiences of being “in the zone.” These usually occur while engaged in some challenging but enjoyable activity, like playing basketball or ballroom dancing. When the challenges presented by the activity are matched by our skills, they are perceived as opportunities rather than obstacles, and our mind enters a groove of exceptionally focused and yet effortlessly maintained attention. During such episodes, awareness merges with action so that we “lose ourselves” in the activity. We feel secure and in control, not because the activity has become predictable, but because we are able to stay engaged, spontaneous, and “in the moment,” responding to challenges as they arise. Such experiences are richly rewarding."31

Happiness Factors

Evidence suggests that we have our own “set point” in a happiness scale. Genetics bias some people to feel happier than others. However we can also choose to engage in activities that raise us towards our maximum potential happiness. So the factors determining happiness include: circumstances 10%, set point 50%, intentional activity 40%.32

Psychological research has found five main personality traits that are broadly stable over time, These “big five” personality traits are openness, conscientiousness, extraversion, agreeableness, and neuroticism. Openness describes to what extent you are receptive to novel ideas, creative experiences and different values. Conscientiousness describes to what extent you are organised, strategic and forward-planning. Extraversion describes to what extent you are inclined to experience positive emotions and how attracted you are to social, stimulating experiences. Agreeableness describes to what extent you are concerned about the feelings of others and how easily you form bonds with people. Neuroticism describes to what extent you react to perceived threats and stressful situations. See

Personality traits and genetics influence our happiness set point. The following list shows estimates of the proportion of the inter-individual variation in happiness accounted for by various factors considered one at a time. Sex 1%, Age 1%, Income 3%, Social class 4%, Marital status 6%, Personality trait of neuroticism 6-28%, Personality trait of extraversion 2-16%, Other personality factors 8-14%.33

Theories of Evolutionary Psychology

If fear evolved to help our ancestors avoid threats, then one might assume that happiness evolved to help us pursue biological benefits such as successful mating, food or good environments. It seems likely that happiness did not evolve for us to feel happy all the time, but rather to keep our ancestors striving for happiness. As Daniel Nettle says, from an evolutionary point of view, “No organism should ever be completely satisfied for more than a short time, because there might be some better way of doing things just around the corner, and the perfectly satisfied individual will never bother to go and discover it. Thus.. there should should be a small nagging gap between our present contentment and a conceivably possible super contentment. Into this vital chink, swarm paddlers of nostalgia, spiritual systems, drugs and all kinds of consumer goods.”34

Negative emotions often feel stronger than positive emotions. Haidt gives the following evolutionary example: If a young animal misses a positive cue for food then another feeding opportunity will come along, but missing the negative cue for a predator means it's genes will fail to propagate.35 Hence, Negativity Bias. See

“Chronic unhappiness is the result of mechanisms internal to ourselves, be it the tyranny of wanting rather than liking, or the hyperactivity of negative emotions. Moreover, it is not that unhappiness is the result of mechanisms within ourselves that have gone wrong. The wanting system is supposed to enslave you, to make you maximise your reproductive success. The negative emotion system is supposed to be hyperactive, because suffering ten false false alarms is better than getting killed. Thus our biggest enemy, if we decide we want to be happy beings, is the very psychology that we have to do it. Fortunately, however, that psychology is pretty smart and pretty flexible, and so can come up with ruses like cognitive behavioural therapy and pleasant activity training to have a dialogue with itself.”36

To be effective, positive psychology must be grounded in realism. Unrealistic positivity might jar our more rational thought processes. The survival of our ancestors may have relied on the ability to realistically appraise threatening situations. A legacy of this evolution, may imply that well-being demands realism.

The Importance of Feeling Sad

Humans evolved to react to change. All positive emotions are transitory. We cannot hold a positive emotion forever. We cannot feel elated all the time. A life of uninterrupted excess would become boring. Sadness is unavoidable, valuable, and necessary to recover from negative events. Sadness provides contrast with pleasure and stops us taking pleasures for granted and helps us to feel joy anew. We can allow positive emotions to come and go while also remaining open to feeling the next positive emotion. Within limits, we can welcome periodic negative sensations as they increase our experience of subsequent positive emotions. Mathematical analysis indicates an optimal ratio of positive experiences and emotions to negative ones should be equal to or greater than 3:1.37

We need moments of negativity in order to notice happiness. Some sadness is inevitable. Optimum experience comes when we move to the top of our happiness range.

Minimising Negativity

IMPORTANT: Some people feel negative thoughts so frequently as to prevent them being able to work, socialise or maintain a home. If you feel this describes you, then seek medical advice. If the first therapist you meet does not meet with your needs, then seek another qualified medical practitioner. If you consider taking your own life, consult a doctor. Today many effective treatments exist for depression. Qualified practitioners with knowledge of an individual case should administer these therapies to maximise their benefit.

Peak-End Rule

“When remembering how good or bad a past experience felt, our judgements seem to be based largely on the average of two factors: how good or bad the peak moment was, and how good or bad the end was. The total amount of pleasure or mean is often neglected.” Endings strongly influence our memories of events.38

Enjoy the Mystery

Unexplained pleasurable events produce longer lasting positive emotions than pleasures that are fully understood. Fully analysing why an experience makes you feel good can reduce its positive affect. People tend to assume they will feel more pleasure with an explanation for why they feel good but, paradoxically, unexplained positive emotions last longer.39

As Ian McEwan, writes in Enduring Love, "We are highly adaptive creatures. The predictable becomes, by definition, background, leaving the attention uncluttered, the better to deal with the random or unexpected."

Other Ways to Increase Happiness

Socialise and, where possible, try to speak well of people.40

Go outside for more than 20 minutes, especially when in good weather.41

Choose any videos you watch. Making thoughtful and deliberate choices over the media you consume can increase your engagement with documentaries and drama.

Many good self help books are intellectually modelled on psychotherapies such as Cognitive Behavioural Therapy. However, self help books might also raise unrealistic expectations. Promised rewards might not materialise even if the reader follows all the prescribed advice.42

Many factors governing happiness tend to remain set (eg personality traits) or tend to be slow to change (eg habitual behaviour). Improving happiness by influencing brain function, such as regular meditation, requires dedication and many weeks of effort. Be realistic in your expectations, but also feel encouraged that dedicated effort applied over months can improve your happiness.

Related Concepts

Broaden and Build Theory concerns the evolution of positive emotions. See

Neuroplasticity means the structures and functions of our brains change and reorganise with continuing experience. See

Final Thoughts

Tip: “Never put anything down to malice that you could attribute to stupidity or ignorance.”

We can fight for justice while still taking the time to appreciate the good around us.

We recommend mindful practice and learning to dance.


Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile".

Haidt, Jonathan 2006 "Happiness Hypothesis: Putting Ancient Wisdom to the Test of Modern Science".

Seligman, Martin E.P. 2002 "Authentic Happiness: Using the New Positive Psychology to Realise Your Potential for Lasting Fulfilment".

Seligman, Martin E.P. 1990 "Learned Optimism: How to Change Your Mind and Your Life".

Csikszentmihalyi, Mihaly 1992 "Flow: The Classic Work on How to Achieve Happiness".

Fredrickson, Barbara 2009 “Positivity: Ground breaking Research Reveals How to Embrace the Hidden Strength of Positive Emotions, Overcome Negativity, and Thrive”.

Gilbert, Daniel 2006 "Stumbling on Happiness".

Bryant, F. B. and Veroff, J. 2006 "Savoring: A New Model of Positive Experience".

Lyubomirsky, Sonja 2008 "The How of Happiness: A Scientific Approach to Getting the Life You Want".

Grenville-Cleave, Bridget and Boniwell, Ilona 2008 "The happiness equation".

Bruya, Brian (Editor) 2010 "Effortless Attention: A New Perspective in the Cognitive Science of Attention and Action" MIT Press.


1Marcus Aurelius 175CE “Meditations” IV, 3.

2Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp157.

3Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" page 49.

4Seligman, Martin E.P. 2002 "Authentic Happiness: Using the New Positive Psychology to Realise Your Potential for Lasting Fulfilment" and Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile".

5Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" Chapter 6.

6Seligman, Martin E.P. 2002 "Authentic Happiness: Using the New Positive Psychology to Realise Your Potential for Lasting Fulfilment" Chapter 9.

7Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" Chapter 5.

8Tse, W.S. and Bond, A.J. 2002 “Serotonergic intervention affects both social dominance and affiliative behaviour” Psychopharmacology 161 pp324-30.

9Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" Chapter 5.

10Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" Chapter 6.

11Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp151.

12Lyubomirsky, S., Sheldon, K. M. and Schkade, D. 2005 "Pursuing Happiness: The Architecture of Sustainable Change" Review of General Psychology 2005, Volume 9, Number 2, pp111–131.


14Seligman, Martin E.P. 2002 "Authentic Happiness: Using the New Positive Psychology to Realise Your Potential for Lasting Fulfilment" page 49.


16Seligman, Martin E.P. 2002 "Authentic Happiness: Using the New Positive Psychology to Realise Your Potential for Lasting Fulfilment" Chapter 7 “Happiness in the Present”. Hedonic_treadmill 2010-01-25

18Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp74.

19Burns, D. D. 1980 “Feeling Good: The New Mood Therapy”.

20Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp34-25.

21Schwarz, N. and Clore, G.L. 1983 Mood, misattribution and judgements on well-being: Informative and directive functions of affective states” Journal of Personality and Social Psychology, Volume 45, pp 513-23.

22Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile"Chapter 1.

23Schwarz, N. and Strack, N. 1999 “Reports on subjective well-being: Judgemental process and their methodological implications” in “Well-being: Foundations of hedonic psychology”, Russell Sage Foundation, New York.

24Strack, N., Schwarz, N. and Gschniedinger, E. 1985 “Happiness and reminiscing: The role of time perspective, mood and mode of thinking” Journal of Personality and Social Psychology, Volume 49, pp 1460-9.

25Haidt, Jonathan 2006 "Happiness Hypothesis: Putting Ancient Wisdom to the Test of Modern Science" pages 238-239.

26Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp148.

27Seligman, Martin E.P. 1990 "Learned Optimism: How to Change Your Mind and Your Life" Chapter 3.

28Seligman, Martin E.P. 1990 "Learned Optimism: How to Change Your Mind and Your Life" Chapter 12.

29Peterson, C. 2006 “A primer in Positive Psychology”.

30Csikszentmihalyi, Mihaly and Nakamura, Jeanne; Bruya, Brian (Editor) 2010 "Effortless Attention: A New Perspective in the Cognitive Science of Attention and Action" MIT Press, page 186.

31Barrett, Nathaniel 29th June 2010 on Bruya, Brian (Editor) 2010 "Effortless Attention: A New Perspective in the Cognitive Science of Attention and Action" MIT Press.


33Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp111.

34Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp45 and pp56.


36Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" page 154.

37Fredrickson, B. L. and Losada, M. 2005 “Positive affect and the complex dynamics of human flourishing” American Psychologist 60(7) pp678-686.

38Kahneman, D., Diener, E. and Schwarz, N. (eds) 1999 “Well-being: Foundations of hedonic psychology” Russell Sage Foundation, New York.

39Wilson, T. D. et al 2005 "The Pleasures of Uncertainty: Prolonging Positive Moods in Ways People Do Not Anticipate" Journal of Personality and Social Psychology, 2005, Vol. 88, No. 1, 5–21.

40Fleeson, W., Malanos, A. B. and Achille, N. M. 2002 "An Intraindividual Process Approach to the Relationship Between Extraversion and Positive Affect: Is Acting Extraverted as “Good” as Being Extraverted?" Journal of Personality and Social Psychology 2002, Volume 83, Number 6, pp1409–1422.

41Keller et. al. 2005 "A Warm Heart and a Clear Head: The Contingent Effects of Weather on Mood and Cognition" Psychological Science 2005, Volume 16, Number 9, pp724-731.

42Nettle, Daniel 2005 "Happiness: The Science Behind Your Smile" pp143-5