Laughing is good. It is actually the best medicine, and has only positive side effects. For example, your stomach hurts from all the laughing. Laughter increases the amount of oxygen in the blood, which helps healing. It can lower the heart rate and burn up calories. 100 laughs can be equal to a ten minutes aerobic workout on a rowing machine, which was reported by Professor William Fry at Stanford University. But anyway, adults laugh only an average of 15 times per day, a preschooler about 400 times. Why is it that way and what can be done to laugh more?