How come people genuinely think laughter is healthy?

Releases endorphines: That help with stress reduction and lowers your blood pressure and reduces cortisol release in you blood leading to benefits to over all health. Mostly speculation as no study that iam aware of documentin all this.

Benefits of laughter: Laughter can actually reduce the amount of stress hormones. In fact, research shows that good humor & laughter may: induce relaxation, boost the immune system, cheer up a blue mood, decrease fear & anxiety, help people cope with cancer & other life-threatening illnesses, reduce your risk of heart disease & heart attack. Embrace the funnier side of life, despite stress. Ref. Vitality(2):2014.