Good questions!

Nearly any physical activity that I do results in some amount of discomfort in some body part these days (I'm 56). But not moving results in even more discomfort not to mention a depressed mood from the lack of endorphins.

I'm still pondering how people ride 400K, 600K, and beyond without saddle pain. I'm still trying to find the right mix of saddle and shorts so that the last 25 miles of a 200K aren't miserable.