Each day, when people contemplate working out, their brains wage an inner battle: to exercise or not to exercise? This has long been written off as a moral battle between laziness and discipline, but new research published in Neuropsychologia suggests that it’s a neural one. The choice to work out, the paper argues, is a conflict between the brain’s most basic instincts and the relentless desire for self-improvement. Whether a person makes it to the gym or not depends on the outcome of two warring parts of the brain.

University of British Columbia Brain Behavior Laboratory post-doc Matthieu Boisgontier, Ph.D., began the study with a central question: We know working out is healthy, so why don’t we do it? He calls this “the exercise paradox:”

“In daily life, this exercise paradox is illustrated when people who have the intention to be physically active take the escalator/elevator rather than the stairs,” Boisgontier tells Inverse. “Our study is the first one to directly analyze the activity of the brain to understand the exercise paradox.”

This is a refreshing take. Most people are aware that exercise is good for health, but that doesn’t make actually doing it any easier. Boisgontier’s research accepts that at our core, we are programmed to be drawn to sedentary behavior. Then he turns to brain imaging to explain why exercising seems so hard, identifying a crucial difference in how hard our brains have to work when thinking about relaxing versus contemplating a workout.

sedentary behavior exercise
The soothing images of sedentary behavior that the team used in this study 

To help identify why we struggle with the exercise paradox, Boisgontier worked with Boris Cheval, Ph.D., a post-doctoral researcher studying exercise physiology at the University of Geneva. They started by showing 29 volunteers —14 of whom were physically active, and 15 who wanted to become physically active — a series of pictures on a computer screen. These images depicted activities aligned with “movement and active lifestyle,” like running or kicking a soccer ball, or “rest and sedentary lifestyle,” like relaxing on the couch. The screen also showed a human figurine that participants could move around using the keyboard.

Then, subjects were asked to make the figurine approach the “physical activity” images and avoid the “sedentary” ones, or vice versa. While they completed this task, the patterns of electrical activity of their brains were measured, showing how hard each person’s brain had to work in order to complete the task. This odd game — called an “approach/avoidance task” — is an established way to uncover how the brain automatically processes information without our knowledge.

exercise experiments
Aside from helping reveal why people hate to exercise, these images are just cool looking 

The results revealed that when people avoided the sedentary behavior cues, their brains showed a flurry of activity — what Cheval calls “an inhibition response” — compared to those who “approached” them.

“People spontaneously tend to approach sedentary behavior, but because the task asked them to avoid sedentary behavior, they had to inhibit their automatic tendency,” he tells Inverse. “The inhibition is evidence that people tend to approach sedentary behavior at the brain level. People are able to avoid sedentary behavior but they have to invest more resources in this task.”

In other words, our brains don’t have to work too hard when we’re thinking about being lazy and avoiding physical activity. Conversely, our brains become more active when we think about working out and avoiding another Netflix binge.

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The subjects' brain had to work much harder to avoid the sedentary behavior (red) versus approach it 

In short, this team captured exactly what happens in the brain when someone contemplates prying themselves off the couch. The brain has to activate a costly “inhibition response” and work hard to overcome that natural tendency to lie around.

Given these findings, it’s impressive that people manage to overcome this internal fight and start working out at all. But of course, just because we better understand the underpinnings of the exercise paradox doesn’t necessarily mean it’s healthy to give into our natural tendencies. Our propensity for laziness seems like it might be a behavior meant to conserve energy, but for most people today, stockpiling calories is simply not a problem.

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