I noticed the same thing. Being fit is such a great feeling.
In contrast, after my hang gliding outing on Sunday (where nothing whatsoever went wrong), the next day I felt like I had been run over by a truck.
Maybe triathlon is what I need, although it is a scary thought.
I'm pretty sure triathlon is not what I need. :-)
Yeah: I'm afraid I might find that (like those highly skilled young women) nothing hurt, and what it would mean is that I was dead.