The next time you're finding it hard to muster up the energy to plow through a difficult task, remember this: believing in yourself will help. 

As cheesy as that sounds, science suggests it's true. Researchers from the University of Hamburg and New York University found that study participants who became mentally energized over the thought of completing a goal became physiologically energized, as well.

To conduct the study, researchers had college students perform what's called a mental contrast. Participants were asked to think about a goal they'd be expected to accomplish in the future. Then they were asked to think about where they stood in relation to that goal at present. 

The goal, in this case, was writing a graduate admissions essay. Students were asked to rate how successful they thought they'd be at achieving the task. In the end, the participants didn't have to write the essay, but after the mental contrasting exercises, researchers took their systolic blood pressure. This served as a measure of their physiological energy.  

The results: when students felt that the task wasn't achievable, their systolic blood pressure went down, compared to the baseline measure taken at the beginning of the exercise. But when students thought it was highly likely that they could write a good essay, their systolic blood pressure went up. 

As cognitive scientist Art Markman pointed out in his recent post, the findings aren't all that surprising since the brain controls both mental function and bodily actions. 

So while you might not be able to completely ditch the coffee or the energy drinks, isn't nice to know that you can be your own source of vitality?