My %#&$@!! Knees. Had surgery on the right one in 2010 and need surgery on the left one now.
And I’m only 26.
And I didn’t play competitive sports.
Doesn’t keep me out of the mountains but it definitely makes me be much more cautious on the routes I take!
I had surgery on both of mine BEFORE I was 18! So yea, thats my nemesis as well!