Usually after stressful life events. I started working out (inconsistently) 7 years ago near the beginning of med school and shortly after a bad breakup. Have been trying to stay consistent with it...

It's such a great stress-reliever, and there's something about actually seeing and feeling the results of hard work. You know it hurts, but the rewards are worth it if you can stay consistent and give it your all. Also, I figured it would be a great examples to the patients I see, which it most certainly has been!