Be choosy about your circle. Select your friendships carefully. "Gather people around you who will reinforce your lifestyle," says Buettner. Okinawans, some of the world's longest-living people, have a tradition of not just forming strong social networks (called moais) but also nurturing them. Kamada Nakazato, 102, never goes a day without meeting her four closest friends—from childhood—for a juicy gossip session. After you identify your inner circle, keep it from dwindling. Make an effort to hang on to good friends by keeping in frequent contact and spending time with them.

Live with intention. In Costa Rica it's called plan de vida. In Okinawa, ikigai. "Across the board, those living the longest had a clear sense of purpose," says Buettner. "You have to know why you get up every morning." Take time to reconnect with your values and reassess your passions and strengths. Then look for activities or classes where you can do more of the things that make you happiest in life.