The Real Reason Exercise Makes You Happy, According To Research On The Brain

Anyone who has ever gone on a run is likely familiar with the ubiquitous "runner's high," that euphoric sense you get after a jog where you feel on top of the world. And that post-workout good mood isn't just anecdotal: Over the years, scientific research has found that, in addition to physical benefits like promoting longevity and healthy eating, exercise actually does help boost your emotions. 

Researchers have been looking into the link between exercise and cognition for several decades. One conclusive and undeniable truth has emerged from these studies: Exercise boosts your mood because it fundamentally changes your brain, both in the moment and over time.

"Right now, the debate in the research world is over how big the benefits of exercise truly are, but those are just details," explains Art Kramer, Ph.D., a professor of psychology and director of the Center for Cognitive and Brain Health at Northeastern University. "What everyone agrees on at this point is that exercise has the ability to change your mood because it has a dramatic impact on your brain."

What kind of impact, you ask? For starters, when you exercise, your heart rate increases and your body pumps more oxygen to your brain. That process can affect your overall positivity, as multiple studies1 have found that a well-oxygenated brain helps manage anxiety and depression2. Other studies have found that exercise may help alleviate depression and anxiety overall3.

Research has also shown that after 20 or 30 minutes of aerobic exercise, your body releases chemicals called endorphins that interact with receptors in your brain that reduce your perception of pain—meaning you're more likely to feel positive and upbeat during a tough workout1. It also releases other mood-enhancing chemicals like serotonin and dopamine that can stick around in your brain for a couple of hours after you exercise. 

"But all of those chemicals are only the beginning," Kramer explains. "On a bigger level, while exercise does have those short-lived mental health benefits, it also actually changes the structure and function of your brain over time," he continues. "The general consensus is that a multitude of beneficial and chronic changes for a healthier brain and mind can happen if you exercise for an hour a day, three days a week."

For example, exercise may generate new neurons in the hippocampus4, the region of the brain associated with memory, learning, and emotions. Because the hippocampus manages your emotions, optimizing it could make you more likely to feel emotionally stable in the long term. "There are hundreds of papers on this topic that date back decades and decades, so it's difficult to sum up all of the nitty-gritty details—but the point is that exercise impacts your brain both in the moment and structurally over time." 

While all physical activity is beneficial, aerobic activity (aka cardio exercises such as running, biking, or swimming) seems to be best for your brain, though it's important to acknowledge that could be because there are simply more studies done on aerobic activity at this point in time. "We do have some research that shows doing yoga and tai chi has a similarly positive effect on the brain as aerobic exercise, but it's not nearly as many studies," Kramer says, meaning it's difficult to give a conclusive answer. 

His advice: Do the exercise you like the most because you will actually do it in the first place—and doing something, whatever it is, is pretty much always better than doing nothing. That, coupled with other healthy practices like getting enough sleep, eating well, and setting aside time to maintain fulfilling relationships, will help guarantee that both your body and your brain are in great shape for years to come.