Joie de vivre. We all know people whose engagement with life can only be described as joyful. Fittingly, nature rewards these happy-go-lucky types: Being optimistic in middle age increases life span by at least 7.5 years—even after accounting for age, gender, socioeconomic status, and physical health, according to a large Yale University survey. What’s behind their hardiness: They minimize the destructive effects of stress.
"Of course, optimists get stressed," says David Snowdon, a professor of neurology at the University of Kentucky who studies aging. "But they automatically turn the response off much more quickly and return to a positive mental and physical state."
Here are four habits that longevity experts say are at the heart of a sunny disposition—and that you can adopt, too.