London - Optimists tend to live longer and have a greater chance of reaching their 85th birthday, says a study.
Experts say those who stay positive cope with stress better, which may limit its effect on health.
They are also more likely to set themselves goals, and believe they will achieve them, which makes them more likely to exercise and eat healthily.
Researchers tracked almost 70 000 women for a decade and almost 1 500 men for 30 years. They were asked how much they agreed with statements including, for women, "In uncertain times, I usually expect the best" and for men, "I usually expect to succeed in things I do".