Most things that will help you live longer -- eating kale, lifting weights, colonoscopies -- aren't particularly pleasant. But what if I told you there was a scientific study that said you could live 15 percent longer simply by doing something that will actually make you smile? 

Thanks to scientists out of Harvard and Boston University, I can deliver just such good news. They recently poured over data on 70,000 people and concluded that just by being an optimist you can extend your life by 14.9 percent on average. 

Cheer up, it could save your life. 

The happy findings come via Science (hat tip to Boing Boing) which reported the findings in brief a few days ago. For the study, published in Proceedings of the National Academy of Sciences, the researchers aggregated data from two studies on both the health and mental outlook of around 70,000 people before crunching the numbers to look for correlations. Here's the headline takeaway:

"After controlling for health conditions, behaviors like diet and exercise, and other demographic information, the scientists were able to show that the most optimistic women (top 25 percent) lived an average of 14.9 percent longer than their more pessimistic peers. For the men the results were a bit less dramatic: The most optimistic of the bunch lived 10.9 percent longer than their peers, on average," Science reports.

"The most optimistic women were also 1.5 times more likely to reach 85 years old than the least optimistic women, whereas the most optimistic men were 1.7 times more likely to make it to that age."  

Why rose-colored glasses can help you live longer

Why does a sunny outlook help people live longer? They researchers suspect the optimistic among us make healthier choices. "An optimistic mindset may promote healthy behaviors like exercise and healthy diets and help individuals resist the temptation of unhealthy impulses like smoking and drinking. Optimists may also handle stress better than pessimists," Science says. 

Though there may be more to the link between rose-colored glasses and longer lives. Previous research has shown that keeping an open and curious attitude towards life also helps you stay healthy and active longer. It's the scientific version of the old saw that "you're only as young as you feel." That means it is also possible that an optimistic outlook helps people stay young by helping them think young, though that's only speculation. 

How to become more optimistic (if you want to)

All of which should have natural optimists gloating, but what about those readers who weren't gifted with an upbeat disposition? First, it should be noted that pessimism has its upsides. Those who are more focused on the negative actually make more money in business and are often more productive, according to research. Moderate anxiety helps you stay safe and remember more

But if you've weighed the pros and cons and actively want to try and be more optimistic, it is possible. Our personalities shift way more over our lives than many of us expect, and you can actively encourage your brain to be more optimistic. The key is cultivating gratitude, which will train you to focus on the bright side, making it easier to see the good in situations going forward. 

That won't just make the world appear a little brighter, it might just help you live a fair bit longer.