What doesn't kill us makes us stronger. That saying from the German philosopher Friedrich Nietzsche (originally "What does not kill me, makes me stronger") has become a cliché, but some studies have concluded that it’s true that adversity—at least in moderation—can be beneficial and even protective when it comes to physical and mental health, which are often connected.
A few years ago, a study from researchers at the University of Buffalo and University of California, Irvine, found that people with chronic back pain who had experienced some adversity during their lives reported less impairment and disability than their counterparts who had suffered either no adverse events (hard to imagine) or overwhelming amounts. Adversity was defined as serious illness or injury to you or a loved one, bereavement, and other major life stresses. In a second study, the same researchers found that people with a moderate amount of lifetime adversity reported better mental health and well-being than those who had suffered lots of adversity or none at all.
While it’s well known that severe adversity increases the risk of physical and mental problems (as in post-traumatic stress disorder), lack of adversity may leave people poorly equipped to deal with stress when it does occur. Overcoming adversity can help us develop resilience, psychological resources, and coping methods, the researchers concluded. It’s the same old U-shaped curve—where people in the middle fare best—that turns up in so many matters of health.
Also see The Surprising Benefits of Stress.