We've all heard the old saying, "If it doesn't kill you, it will make you stronger," in some form or another. Most likely from our parents, or teachers, or someone else trying to toughen us up. And it turns out, they were right.

A new study published in the December issue of Current Directions in Psychological Science, has found that although we all hope for a life free and clear of stress, the happiest and healthiest people are those who have had at least some early exposure to tough experiences. 

It can be tricky to pinpoint exactly how much stress is the right amount. Too much stress — such as living in extreme poverty or experiencing a harrowing natural disaster — create large amounts of uncontrollable stress, which can be psychologically damaging. But as it turns out, it's also harmful not to experience any stress at all.

In his study, Dr. Mark Seery, associate professor of psychology at the University of Buffalo, found that people who experienced a lot of trauma over the course of their lives were more distressed in general — but so were the folks who had experienced no trauma at all. Those who fared the best were the people who had experienced some negative events — things like serious illness or injury, parental divorce, or death of a family member.

One theory is that small amounts of stress give people the tools they need to cope with hardship, making it easier for them to handle tough experiences later on. But Seery wants to make it clear that he's not telling parents to abuse their kids so they’ll grow up to be happier and healthier adults.

"Negative events have negative effects," he says. "I really look at this as being a silver lining. Just because something bad has happened to someone doesn’t mean they’re doomed to be damaged from that point on."

It's true: What doesn't kill you will make you stronger
New study finds an old saying is true: Tough experiences will strengthen you.