I am Mike's generation and a few years ago I started running (up to 30k) and using kettlebells and weights. I got leaner, fitter, and stronger than when I was a competitive athlete in my late teens. The difference, and it was huge, I became prone to joint injury and muscle tear, and injury recovery is months, if not years, instead of days or weeks.

I would not get in a ring with anyone. Hell, I conceal carry a pistol, and plan to escape all non life-threatening encounters.