Well, I did half an hour of group CrossFit at CrossFit 661. It was one of these massive workouts. I did half an hour of it and then stopped. I could barely walk to the car. I had to pull over from the pain on the way home and chill out a little bit until my legs stopped hurting so much. The details of the workout are unimportant.
I am going to discontinue my group membership at the end of this month. It is just too much for my old body to take. I will still do CrossFit workouts at home.