Your Brain Doesn’t Want You to Exercise

If the benefits of physical activity were distilled into a pill, everyone would be on it. Studies show that moving improves nearly every aspect of health: boosting sleep, strength, and mental well-being while slashing the risk of chronic conditions and premature death. What’s more, studies show that exercise has a positive impact even when done in very short chunks and with no equipment or fancy gym membership required.

Still, most people don’t exercise nearly enough. According to data published in 2023, less than a third of U.S. adults get the government-recommended amount of physical activity in their free time: at least 20 minutes of moderate-intensity aerobic movement (think brisk walking) per day, plus a couple muscle-strengthening sessions (such as resistance training) each week.

Why is it so tough to get people to do something so good for and accessible to them? Physical limitations and health problems are certainly a factor for many people, since more than half of U.S. adults have some kind of chronic condition. Modern life deserves much of the blame, too, with long, sedentary work days and infrastructure that often makes it easier to hop in the car than walk or bike somewhere. And studies have long shown that people who don't make much money are less likely to exercise than wealthier people, in part because they may live in areas with relatively few spaces where it’s safe and pleasant to be active.

But research suggests there’s another obstacle that affects all of us: our brains don’t want us to exercise.

For most of human existence, people had to be physically active to carry out the basic functions of life, such as finding or growing food. Humans evolved to tolerate a high level of activity—but also to gravitate toward rest when possible, to conserve energy for when movement was either necessary or pleasurable, explains Daniel Lieberman, a human evolutionary biologist and author of Exercised: Why Something We Never Evolved to Do is Healthy and Rewarding.

In other words, hunter gatherers weren't out jogging to burn extra calories. From an evolutionary perspective, "that would be a stupid thing to do," Lieberman says. "You're wasting energy on something that's not going to give you any benefit whatsoever."

As a society, we no longer move much in the course of daily life, but the evolutionary instinct to conserve energy remains, Lieberman says. “That disinclination, that reluctance, that voice that says, ‘I don’t want to [exercise],’ is completely normal and natural,” he says.

Physical-activity researcher Matthieu Boisgontier, an associate professor at the University of Ottawa, demonstrated that phenomenon in a 2018 study. While hooked up to brain-activity monitors, people were given control of a digital avatar. They were told to move the avatar away from images of sedentary behavior that popped up on their computer screens and toward images of physical activity. Boisgontier and his colleagues found that avoiding sedentary behavior took more brain power, which suggests “we have an automatic tendency” to choose relaxing over moving, he says.

That conclusion shows up repeatedly in research. Studies show, for example, that people consistently choose to take an escalator instead of the stairs. That natural instinct isn’t inherently bad—it’s just that modern life gives us so many chances to give in to our preference for rest that “we have reached an extreme that is no longer beneficial to our health,” Boisgontier says.

Many people also subconsciously harbor negative feelings toward exercise that go back to childhood, says Jackie Hargreaves, a senior lecturer on sport and exercise psychology at the U.K.’s Leeds Beckett University. A gym-class embarrassment or unpleasant experience with a youth sports team can make a person avoid working out well into adulthood, Hargreaves says.

Sometimes it’s also a confidence issue. Research suggests people who view themselves as competent exercisers are more likely to stick to a regular routine, while people who think the opposite may struggle to find consistent motivation, says Stefanie Williams, a behavioral scientist who works with a U.K. organization that translates health research into practice.

Feeling good about your ability is crucial to finding the motivation to exercise, says Sam Zizzi, an exercise psychologist at West Virginia University. He recommends starting small—perhaps walking just a few minutes per day at first—and building on that progress over time. Observing a peer doing what you’d like to do, particularly if they share your age, gender, or health status, can also help you realize you can accomplish it, too, Williams says.

A counterintuitive way to build confidence, Lieberman adds, is to simply recognize the ways your brain sets you up to fail. “When people struggle to exercise, they’re told they’re lazy or there’s something wrong with them,” when in reality, people who exercise purely for fitness are the ones working against their natural instincts, Lieberman says. Replacing guilt and shame with self compassion—and an understanding of how the human brain works—can go a long way.

So can reframing what counts as exercise. You don’t need to spend an hour lifting weights at the gym; even taking a few minutes per day to dance in your kitchen or weed the garden is great for your mind and body, numerous studies show. “It’s not about going out and doing vigorous, competitive sport,” Hargreaves says. “It’s about moving,” and finding ways to move that are actually enjoyable.

Finally, Zizzi recommends making exercise “serve a double purpose”—perhaps by planning a bike ride with friends so your workout doubles as a social outing, or making an existing work meeting a walk-and-talk. Intertwining exercise with something you already want or need to do, Zizzi says, can make it easier to ignore the part of your brain that’s telling you it’s better to park yourself on the couch.