After my workout with Billy on Sunday, the pain and soreness continued to get worse. I thought that the quick cardio bout on Monday would help to loosen up my muscles, but I was dead wrong. Come Tuesday, I had to walk down the stairs at work sideways (again). I felt pretty far from a young, healthy thirty-one year old. And all I kept thinking about was how-only a few days ago-I reflected on the need to listen to my instincts and not overdo it in the gym.  What's going on here?

I know I'm...