Legend has it that a Greek soldier named Pheidippides ran roughly 26 miles from Marathon to Athens in 490 BC to announce a Greek victory over the Persians. After the run, he is said to have delivered the news and then collapsed and died. His story has since been romanticized as the origin of the marathon and a testament to human endurance.
Winston Churchill famously once said, “Healthy citizens are the greatest asset any country can have.” He may have been speaking in the context of war and national strength, but the sentiment still resonates on a personal level and carries the same truth: we rise when we set our bodies and minds to challenges. In the decades since, science has repeatedly shown that one of the most powerful defenses we have against the invisible battles of the mind, like depression, comes from something both simple and demanding: moving our bodies.
A meta-analysis from 2016, drawing on data from over one million people, makes the connection clearer than ever. Researchers led by Felipe B. Schuch at Centro Universitário La Salle examined three large studies—two from the United States and one from Sweden—covering 1,128,290 participants, 98 percent of whom were men. Fitness was measured in straightforward but telling ways: performance on a treadmill, stamina on a stationary bike, and the ability to climb the equivalent of several flights of stairs.
The findings were striking.
People with low cardiorespiratory fitness had a 75 percent higher risk of developing depression. Even those with only moderate fitness faced a 23 percent higher risk compared to their most fit peers. Schuch summarized the core message in an interview with PsyPost: improving fitness through physical activity isn’t just about cardiovascular health or endurance, it’s a direct, actionable strategy to prevent depression before it starts.
This research builds on a growing body of evidence tying physical and mental health into a single, inseparable story. Meanwhile, controlled trials show a robust effect: aerobic, resistance, or combined exercise regimens reduced depressive symptoms with a large magnitude of benefit (PubMedPMC). Similarly, in young people, aerobic workouts—even sessions under 40 minutes—consistently lifted mood across varying durations according to PubMed.
Going further back, a 2006 study showed that when college students who didn’t exercise began going to the gym just a few times a week, they gained what researchers called a greater “capacity for self-regulation.” That meant they were more likely to handle stress without turning to substances, and more consistent in healthy behaviors like eating well, spending wisely, and keeping up with studies.
Besides science, it’s a lived experience. Ask anyone who’s made exercise a consistent habit, and they’ll describe more than just physical changes. There’s a steadiness that comes from keeping a promise to yourself, from pushing through discomfort, from feeling your lungs and muscles grow stronger. These are the same qualities that guard against life’s inevitable setbacks.
The lesson is both old and new. Ancient philosophers like Hippocrates understood that “walking is man’s best medicine,” and modern science is now quantifying why. Our bodies were built to move, and when they do, the brain benefits in ways that protect our mental resilience. The key is not to wait until life feels overwhelming to start.
As the weather turns colder and the temptation to stay inside grows stronger, there’s even more reason to lace up your shoes, step outside, or head to the gym. Your future self (facing the normal stresses, losses, and unexpected changes of life) will thank you for building the endurance now.
Roman saying goes, mens sana in corpore Sano, meaning a healthy mind in a healthy body. So if you’re looking for a reason to keep running or cycling, cardio may not solve every problem, but it strengthens the one tool you carry into every battle: yourself. And that is worth every step, every mile, and every flight of stairs.
