Culture & Society

How Exercise Recommendations Might Work against Us

When it comes to physical activity, how well we think we’re doing can influence how much we move and how we feel.

March 10, 2020

| by Jane Bianchi


Rashaad Gomez practices parkour in a park in New York. Credit: Reuters/Carlo Allegri

Research shows positive mindsets about our health can improve our activity levels. | Reuters/Carlo Allegri

If public health officials in the U.S. government are worried Americans aren’t exercising enough, logic suggests a simple solution: Tell us how much to exercise.

But here’s the thing: They did. Their national physical activity recommendations have been well publicized. And a whopping 78% of us still aren’t meeting them.

“This idea that we just need to educate people and give them the right information and then they will behave better or change their lifestyles, that’s just not true,” says Octavia Zahrt, a doctoral candidate in organizational behavior at the Stanford Graduate School of Business. “Most people actually know that exercise is important, but that’s not enough to motivate them.”

So what is? The key, Zahrt argues, may be in shifting our mindsets.

How Negative Mindsets Can Hurt Us

When Zahrt moved from London to the San Francisco Bay Area, she experienced a culture shock. In terms of her regular exercise routines in England, she had biked to work and had done some yoga and housework and had thought that was plenty. But in California, she noticed fitness studios on practically every corner and a focus on vigorous activities.

“I just felt like I was suddenly surrounded by people who exercised all the time. I suddenly felt really unfit and unhealthy, just because I was comparing myself with a different set of people,” she says.

Based on this experience, she developed the idea that no matter how active people actually are, they can hold the mindset that their physical activity level is adequate and healthy, or inadequate and unhealthy, and that these mindsets may have real consequences for people’s well-being.

These thoughts led to a November 2017 study in the journal Health Psychology that she coauthored with Alia Crum, an assistant professor of psychology at Stanford. It showed that this type of negative mindset may have detrimental effects on health and longevity. In their study, participants who believed they were less active than their peers had a 71% higher mortality risk than those who perceived themselves as more active than their peers — and this finding held true no matter how active they actually were.

Define “Exercise”

In their latest study (published this month in the journal Preventive Medicine Reports), they looked beyond peer influence to examine how recommendations affect our behavior.

There were two parts to the study.

In part one, 157 participants reported their level of physical activity in the previous week and then were randomly assigned to read one of two sets of U.S. exercise guidelines:

  • The 1996 guidelines from the Centers for Disease Control and Prevention: These are considered “low and liberal” because they recommend 150+ minutes of moderate aerobic activity per week and count lighter, everyday activities such as walking or housework as exercise.
  • The 2018 guidelines from the U.S. Department of Health and Human Services: These are considered “high and stringent” because they recommend either 150+ minutes of moderate or 75+ minutes of vigorous aerobic activity per week, plus muscle strengthening at least twice a week. They do not count lighter, everyday activities as exercise.

Immediately after, participants were asked questions about their mindsets regarding the adequacy and health consequences of their current level of physical activity. One week later, they were asked about their current level of physical activity and how healthy they thought they were.

The findings: Those who were exposed to the low and liberal guidelines formed more positive mindsets and believed that their activity levels were adequate and healthy, compared with those who read the high and stringent guidelines.

Importantly, the researchers found, this positive mindset predicted greater physical activity and perceived health one week later. Those who read the high and stringent guidelines appeared to lose motivation and got, on average, one hour and 20 minutes less of moderate physical activity the following week. On the other hand, those who read the low and liberal guidelines mostly maintained their level of physical activity the following week.


I just felt like I was suddenly surrounded by people who exercised all the time. I suddenly felt really unfit and unhealthy, just because I was comparing myself with a different set of people.
Octavia Zahrt

Part two of the study was similar, except the researchers added in one more measurement: self-efficacy. In other words, how confident are you that you’ll be able to motivate yourself to exercise given everything else that’s going on in your life — for example, go for a run at the end of a really long, tiring day at work?

The researchers found a three-step domino effect: Low and liberal guidelines led people to adopt a more positive mindset. These positive mindsets led to higher self-efficacy measures. And those with high self-efficacy were more likely to be active the week after viewing the guidelines.

These discoveries raise an important question: How useful are demanding, strict guidelines if they don’t inspire the desired outcome? “This was a wake-up call that we have to look more into these complex psychological relationships to be able to help people most effectively,” says Zahrt.

Tweaking Public Health Messaging

While these findings are preliminary and need to be replicated and confirmed in future studies, Zahrt says, there’s a lot we can learn here.

Mostly, Zahrt would love to see public health officials collaborate more with psychologists and modify their exercise messaging. “We could help people see all the ways in which they’re already getting physical activity in their everyday lives. For example, lots of people think that the only adequate exercise is running or going to the gym and weight lifting, and they underestimate the positive impacts of walking the dog, carrying a child, or cleaning the home,” says Zahrt. “It helps people to think ‘Well, maybe I can improve on that’ rather than ‘Oh, I’m doing nothing and I have no idea how I can ever live up to the guidelines.’”

Zahrt’s next project explores the intersection of exercise, mindsets, and technology. She’s analyzing how people respond, both mentally and physically, when fitness trackers provide certain types of feedback.

Perhaps there’s one overarching lesson from all of Zahrt’s research that applies to people in any industry: be kind to ourselves when we’re trying to achieve a goal, and celebrate every win. That tiny change in outlook might just keep you going — and yield big results.

“Being more mindful and appreciating every small step along the way is a great way to stay positive and motivated during goal pursuit and to boost the benefits that we get from our physical activities,” says Zahrt.

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