The warm feeling you get from making someone feel better may prolong your own life. A 14-year study of 2,700 people in Tecumseh, Michigan, found a decline in the mortality rate of men who did volunteer work, compared with that of men who didn't. Another study, at Harvard, showed a rise in disease-fighting antibodies in the saliva of students seeing a film about the work among Calcutta's (now Kolkata) poor of Mother Teresa (died in 1997), one of the most admired altruists of this or any other era.
From surveys of people regularly involved in helping others, the picture emerges of altruism lightening depression and bringing increased energy. Many volunteers speak of a "helper's calm" much like the runner's high that comes with exercise. Helping people, like exercise, seems to have a calming effect on the brain and body and may reduce heart stress by curbing anger and irritability.