Final answer:
Laughter strengthens the immune system, increases heart rate and blood pressure like physical exercise, and provides psychological benefits by helping people cope with stressors and encouraging social bonding.
Step-by-step explanation:
The saying "laughter is the best medicine" has scientific support: Laughter boosts the immune system. It also causes temporary increases in heart rate and blood pressure, effects similar to those of physical exercise. On a psychological level, laughter helps people gain distance from stressors and fosters social bonding.