Then one day, a concerned business associate called and asked him to go for a run. Though Dr. Maroon could barely get out of bed, the associate convinced him to throw on an old pair of scrubs and give it a shot.

“I was exhausted and fatigued—but that night was the first night I had slept in three or four months,” Dr. Maroon says.

He slowly but surely kept at it, and even started integrating swimming and cycling into his new fitness regimen, eventually working up to becoming a triathlete. Looking back, he realized that he had been healing his brain with his body. Exercise is one way to prevent depression, but it can also treat depression since physical activity stimulates the brain to form new neural connections, which improves brain health overall. After Dr. Maroon was able to start practicing neurosurgery again, he even found he was a better, “more empathetic” doctor for patients.

While exercise helped Dr. Maroon rebuild after the life quake, the experience also made him rethink his approach to life as a former “workaholic.” Which is why, today, the longevity expert’s tip for staying mentally and physically sharp is to cultivate balance in your life and in a world rife with global and personal challenges.

“You have to have that if you’re going to function at peak performance,” Dr. Maroon says.

Balance is easier said than done, but Dr. Maroon says a useful exercise is to think of the four components of your life as the four sides of a square. The four sides are work, family/social, physical, and spiritual. The length of a side represents the amount of time spent and importance given to that aspect. So, with a pen on a piece of paper, draw your square. Seriously: Go ahead and actually do it. If one side is longer or shorter than any other, you’ll get more of a trapezoid than a square, and you can visually see whether your time and priorities are out of whack. Cultivating balance means equalizing those sides to form those 90-degree angles.

Of course, there are times when one part of our life takes more precedence, and experts agree that’s okay. The key is to make sure that it’s a conscious choice.

“Have mindfulness and awareness,” Dr. Maroon says. “Most people, like I did myself, are automatons. I functioned, I went through the day, I did everything reacting to all of the sensory input from other people and other circumstances without really being aware of where my life was going or what I was doing. Bring awareness and mindfulness on a daily basis to one’s square.”

For Dr. Maroon, that balance forms the foundation for reducing stress, integrating physical activity, pursuing meaning, and nourishing the body, in a way that contributes to both mental and physical sharpness. Which he sees as closely interconnected.

“The things that enhance mental sharpness also enhance peak performance physically,” Dr. Maroon says. “They’re complementary.”