When I was that age my main exercise was commuting by running or biking. I got additional sporadic exercise doing miscellaneous sports. Having kids made it very hard to do more than that. I’m not working now and have the time and energy to do much broader and consistent exercise.

Turning your commute into your exercise regimen is great. Be warned though that the human body is great at optimizing and will quickly adapt to that specific routine. When you vary off that routine you’ll find you’re not in as great of shape as you thought. But you’ll be miles ahead from where you’d be otherwise.