system
A chat on subreddit /r/NoStupidQuestions
human
Weed jacks up my heart rate and instantly makes me want to get up and move, I've never understood how it can mellow people out. I use it before working out.
gpt
My MD and Pharmacist I met with before getting my medical marijuana card both explained that because everyone has variations in their cannabinoid receptor systems, the effects of cannabis differs from person to person. Not too surprising in general; but they also both stated that it can vary so much as a certain strain or ingredient ratio can make one person calm, another person sleepy, and another person energized. The pharmacist was supposed to recommend products she thought would work best for my health concerns, but it basically boiled down to "well this one GENERALLY does this, but there's no way to know for sure for you until you just try it. Oh, also dosage can change your reaction too so try it in different amounts and just start low and feel it out and decide what's right for you". 
Lol. 
It was a noble effort to educate me, but ultimately the most bizarre medication appointment I've ever had. With any other traditional pharmaceutical they just roll the dice on trying a medicine on you, but they tell you exactly which one to take, and exactly how much, how often, and where to pick it up. This was like - have at it, experiment and figure it out! 

The combination of a cannabinoid system that's unique in each person, and barely any research on it's use because it's been a federally restricted substance for decades, add up to a lot of "well we don't really know for sure".

All this being said, my personal experience is that using it for the last 5 weeks has made a hugely positive impact on my mental health. I'm really grateful I can legally use it, and agree 1000% that it is better for you than alcohol.