“Twenty years from now you will be more disappointed by the things you didn’t do than by the ones you did do.” ~Mark Twain

Let me set the scene.

It’s a blistering summer day in Miami—the kind where the humidity hugs you tighter than your ex at a high school reunion, and the air feels like you’re swimming through warm soup. Not exactly the kind of weather that makes you want to move, let alone sweat through a surprise death-match workout on Muscle Beach.

But there I was.

The trainer—clearly a drill sergeant in a past life—barks out: “One more …