The following article comes from the U.S. News ebook, How to Live to 100.
Helping our fellow man has long been seen as an altruistic behavioral model. But it turns out that more selfish motives—pleasing friends, doing what you want—are more successful causes of effective volunteering. Whatever the motive, volunteering improves the health, happiness, and in some cases, the longevity of volunteers. Children who volunteer are more likely to grow up to be adults who volunteer. Even unwilling children who are forced to volunteer fare better than kids who don’t volunteer. And in a virtuous circle, communities with lots of volunteers are more stable and better places to live, which in turn further boosts volunteerism.