What's the 15th largest cause of death in the United States?

If you guessed homicide, skin cancer, or AIDS, nice try, but not correct. According to a fascinating TED talk by Stanford University health psychologist Kelly McGonigal, new studies suggest the answer might be stress. A large study, she reveals, estimated that stress kills up to 20,000 Americans a year.

So how on earth could McGonigal go on to suggest that you make stress your friend? It turns out that only a particular kind of stress takes a serious toll of your health.

What kind? The kind you believe is bad for you.

Stress isn't bad for your health...

Marshaling a boatload of scientific data, McGonigal explains that what makes stress harmful isn't the basic physical reaction that causes your heart to pound and your palms to sweat, but your belief that this is a bad feeling.

Think of those changes as a positive mechanism your body has implemented to prepare you to meet challenges and your constricted blood vessels relax, ensuring that elevated heart rate isn't damaging. Instead, it's roughly similar to what happens in the body when we experience joy or courage.

"When you change your mind about stress, you can change your body's response to stress," McGonigal says. You can, she believes, actually "get better at stress" so it's no longer harmful to your health.

...thinking stress is bad for you is.

What's more, she continues, your body's stress response actually has other benefits based on the hormone oxytocin. Generally known in the popular press as "the cuddle hormone," McGonigal reveals it is also released when you're stressed. You wouldn't necessarily think a high-pressure situation would be a great time for a cuddle, but oxytocin is actually there to drive you to seek social support to help you in difficult times.

"When life is difficult," she emphasizes, "your stress response wants you to be surrounded by people who care about you." And Oxytocin doesn't just drive you to build up your social connections and, with them, your own resilience to stress, it's also a natural anti-inflammatory that pushes your blood vessels to stay relaxed and helps to heal any stress-induced cardiovasculatory damage.

Your body, in other words, has built-in stress protection. As long as you understand this and both embrace your stress rather than battling it and reach out for social support when you're under pressure, "the harmful effects of stress on your health are not inevitable," McGonigal concludes. "When you choose to connect with others under stress, you can create resilience."

Check out the complete talk below. If you have a lot of stress, it's 15-minutes that could save your life.