The Surprising Tweak That Makes Workouts More Effective

You know that not getting regular exercise can be bad for your health. But here’s a surprising twist: Apparently, just thinking that you’re not exercising as much as you should may be harmful, too. In a new study in the journal Health Psychology, people who thought they were less active than their peers had a greater chance of dying younger—even if their actual activity levels were the same.

The research suggests that the health perks of exercise may come not just from the physical movements, but also how people think and feel about them, as well. In other words, people who feel like slackers may not be getting all the benefits they should be from their workouts.

Lead author Octavia Zahrt, a Stanford PhD student in organizational behavior, based her research on a personal experience. “I am from Germany, and back there I felt really good about my activity level,” she says. “I biked to work, and went to the gym maybe once a week.”

When she moved to California, she was suddenly “surrounded by people who exercise all the time,” she says. “Compared to them I felt really inactive, and I developed what I know now was a really negative mindset about my physical activity.”

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So Zahrt and her faculty advisor, Alia Crum, decided to study whether this attitude could have an effect on long-term health. To do so, they analyzed data from 61,141 adults who were surveyed between 1990 and 2006 and followed until 2011.

The adults only answered questions about their activity levels, and some also wore accelerometers to track their real-time activity for a week. In addition, all participants were asked, “Would you say that you are physically more active, less active, or about as active as other persons your age?”

After adjusting their sample to control for factors such as disability, general health status, and demographics, the researchers found that people who believed they were less active than others were 71% more likely to die during the study’s follow-up period—even when activity levels was controlled for, too. In fact, they found that people’s perceptions about their own physical activity levels frequently did not match up with reality.

“It can be easy to compare how much exercise we get with the people around us, as opposed to what’s recommended for everyone,” says Zahrt. “Plus, a lot of people think that exercise has to mean running or going to the gym, and they don’t give themselves credit for all of the other activity they do—cleaning their house, walking to the store, carrying their kids, those sorts of things.”

People who shortchange themselves in this way could be unknowingly sabotaging their health, say the study authors. Meanwhile, those who feel good about their fitness level may benefit as much from their attitude as they do from the physical activity itself.

Crum, assistant professor of psychology and director of Stanford’s Mind and Body Lab, first studied the “placebo effect” of exercise back in 2007. “What’s surprising to me is how robust the accumulated evidence is on the power of mindset in shaping our health,” she says, “and yet people are still so shocked when they hear results like these.”

That’s not to say that exercise doesn’t have real physical health benefits, Crum is quick to point out. “This is not an excuse to just stop doing anything but believe you’re doing everything,” she says. “It’s a reminder that, yes, you should work to get active in your life—but you should also be mindful of those negative thoughts that can creep in and the effects they might have.”

“Just because you didn’t get to that Spin class or that fancy new fitness class, doesn’t mean you’re not as healthy as those who do,” Crum adds. Zahrt agrees: “If we can change our perceptions to view all activity as good activity,” she says, “we think that could be a first and really important step to improving our health.”

This article originally appeared on Health.com