In a study involving more than 20,000 men and woman with an average 11 year follow-up evaluation, researchers were able to identify 4 healthy habits that can potentially add an average of 14 years to one's life. Put another way, those practicing the 4 healthy habits as compared to those not practicing any of the 4 healthy habits will live, on average, 14 years longer. The 4 healthy habits are (1) Don't smoke, or, quit smoking, (2) Eat 5 servings of fruit and vegetables daily, (3) Exercise, and (4) Drink in moderation. According to researcher findings, the most important healthy habit to practice was to stop smoking followed by eating 5 servings of fruits and vegetables daily.
Source: PLoS Medicine. January 2008, Volume 5, Issue 1.