Optimism, it turns out, won't just make you happier. It might also help you live longer.

That's the conclusion of a new study out of the Harvard School of Public Health that tracked a massive sample of 70,000 women enrolled in the ongoing Nurses' Health Study, asking them a series of questions to gauge their level of positivity and monitoring their health and mortality from 2004 to 2012.

The headline conclusion is startling: the most optimistic women were 30 percent less likely to die from any of the serious illness tracked by the study during the study period.

A dose of daily positivity is now doctor's orders.

If you want more details that indicate optimism really can save your life, here they are: The most optimistic women had a 16 percent lower risk of dying from cancer; 38 percent lower risk of dying from heart disease; 39 percent lower risk of dying from a stroke; 38 percent lower risk of dying from respiratory disease; and 52 percent lower risk of dying from infection.

Looking at these results, the doctors behind the research came to the same conclusion as any reasonable layperson: it apparently pays to cultivate some positivity.

"Our new findings suggest that we should make efforts to boost optimism, which has been shown to be associated with healthier behaviors and healthier ways of coping with life challenges," Eric Kim, co-lead author of the study, commented in the Harvard Gazette announcement of the findings.

How to train yourself to be an optimist.

But, you might ask, is it really possible to train yourself to be more positive? Isn't an optimistic or pessimistic outlook largely a matter of inborn character? The short answer to questions along these lines is no.

Though we're all born with a proclivity for some amount of gloom or cheer, learned behavior can play a huge role in your level of optimism. "Previous studies have shown that optimism can be altered with relatively uncomplicated and low-cost interventions - even something as simple as having people write down and think about the best possible outcomes for various areas of their lives, such as careers or friendships," said the study's other lead author Kaitlin Hagan.

What are these simple, low-cost optimism-boosting interventions? Hagan mentions a perpetual favorite of positive psychologists, gratitude, but others include mindfulness, simple acts of kindness, deep breathing, and avoiding complainers. You can read much more about all these science-backed positivity boosters here on Inc.com.