Your brain doesn’t know the difference between fake (or faux) and real smiles/laughter. So when you do these things, your brain releases endorphins and other happy hormones throughout your body. And then your body will want more and more of this happy feeling, cause we all know it likes it better than the opposite emotion, so you’ll start to “automatically” feel happier in your life. Smiling also reduces stress and improves immunity. So come on, show me some of them fake smiles, or laugh your ass off for no reason at all!!!
… shit, I really need to take my own advice on this one ;)