[sidebar]Here are three characteristics that may boost life expectancy: Your glass is half full.A study that analyzed 243 elderly people (average age: 97.6) found that most were more optimistic and easygoing than the general population. If your outlook could be sunnier, write down a few things you’re grateful for daily. You’re everyone’s pal.Having strong social relationships can raise survival odds by 50%, found researchers from Brigham Young University. Not a social butterfly? Start small: Invite some pals to lunch, or consider starting a book club. You’re never late.Conscientiousness (being detail oriented and responsible and always wanting to do a good job) is consistently associated with longevity, says Dr. Hill. Raise your conscientiousness by making (and using) to-do lists. More from Prevention: Surprising Signs You’ll Live To Be 100