According to the Mayo Clinic Proceedings, between 1962 and 1965, Mayo researchers had 839 patients take a personality test. They classified 124 of these patients as optimists, 197 as pessimists and the rest were considered mixed. Then the researchers waited 30 years to find out what happened to the people in their study.
They were able to trace 723 people, and what they found was rather dramatic.
Optimists, and even those who were mixed but with a generally favorable outlook, had a 19 percent better chance of surviving during the 30-year period than the pessimists did.