The Upside of Stress

Kelly McGonigal spent years giving talks and teaching a course at Stanford that boiled down to one message: stress is bad for you, so everyone's mission should be to reduce stress as much as possible. She delivered that message with conviction, citing study after study linking stress to heart problems, weak immunity and even early death.

The problem is that, while reviewing the latest research to update her own course, she ran into data that didn't match the speech she had been repeating for years. People who reported a lot of stress were not, on that basis alone, at higher risk of anything. What made the difference was something else: what the person believed about that stress.

McGonigal decided to do what few well-known people do: she admitted publicly that she was wrong. The book is born from that discomfort, and she calls the change of mind the hardest turnaround of her career, because it meant dismantling a message she herself had helped spread for years.

McGonigal's turnaround has a name and a date: a study led by Abiola Keller, published in 2012, that followed thousands of adults in the United States for several years, asking two simple questions: how much stress the person reported having had in the previous year, and whether they thought that stress was bad for their health.

The result bothered a lot of people in the field. People who reported a lot of stress and believed stress was harmful showed a higher risk of dying during the period studied. People who reported the same amount of stress but did not believe it was harmful did not show that increased risk, even though they were exposed to the same amount of day-to-day pressure.

It is an observational study, so it shows an association between belief and risk, and it doesn't prove on its own that changing your mind about stress changes anyone's fate. But the finding was strong enough to plant the central question of the book: could part of the damage we blame on stress actually come from the certainty that it is going to hurt us?

The central idea of the book has a technical name: mindset, the set of beliefs a person carries about something that, without them noticing, changes the way the body and mind react to that thing. It is not willpower or shallow positive thinking, it is belief, plain and simple, formed over a lifetime by everything you've heard on the subject.

McGonigal uses stress as the example, but the mechanism applies to other beliefs too: two people in the same stressful event, with the same body behind them, can come out with very different results depending on what each one decided that tightness in the chest meant.