People who see the world through rose-colored glasses live longer than those who don’t, and are more likely to achieve “exceptional longevity,” that is, live until age 85 and beyond, according to decades of research by Harvard University’s T.H. Chan School of Public Health, Boston University School of Medicine, and the National Center for PTSD at VA Boston Healthcare System.

“Research on the reason why optimism matters so much remains to be done, but the link between optimism and health is becoming more evident,” the study’s senior author, Fran Grodstein, ScD, professor of epidemiology at Harvard’s School of Public Health and professor of medicine at Harvard Medical School, said in a statement.

The study, published in the journal Proceedings of the National Academy of Sciences, tracked nearly 70,000 women for a decade, and more than 1,400 men for three decades. Participants filled out one of two well-established tests, both designed as research tools and widely used since the 1990s to measure optimism and pessimism. Participants also completed surveys on their general health and lifestyle habits known to affect health, such as diet and smoking.

The most optimistic men and women of the group lived roughly 11% to 15% longer than the average of the group. They were also 50% to 70% more likely to reach age 85 than the least optimistic group. Optimists kept their edge on longevity even after researchers controlled for age, education, chronic diseases, and health of lifestyle.

Related on The Swaddle:

Feeling Young Might Mean Your Brain Is Aging More Slowly

The study was not designed to determine how and why optimism might contribute to longevity, but researchers suggest a connection between a sunnier outlook and a healthier lifestyle. Additionally, “other research suggests that more optimistic people may be able to regulate emotions and behavior as well as bounce back from stressors and difficulties more effectively,” senior author Laura Kubzansky, Ph.D., MPH, a professor of social and behavioral sciences at Harvard, said in the statement.

The link between optimism and longevity offers one more path to promoting healthy aging, researchers say: A 2016 analysis of all available research into learning optimism suggests that it is indeed possible to make one’s outlook on life more positive. One such intervention, reports Scientific American, is to spend five minutes each day thinking positively about one’s future self; known as the Best Possible Self exercise, it has been shown to increase optimism. But optimism interventions are far from perfect — highly dependent on the individual engaging in them, the meta-analysis concluded. After all, a half-full glass only matters if it’s your glass.