There are already several pages of posts, so probably not much new I can add.
Paddling is one of the only things I can still do at a reasonably high level. My paddling strength is probably at over 80% of what it was when I was 30, but I'm having to train harder to get there.
One aspect of paddling I can't do is portaging. My hips and knees just can't take it. I may have done my last Boundary Waters trip, but I'm looking over the maps, trying to find routes with little to no portaging.
I used to have friends that I paddled with. They have either passed away or we are no longer on good terms. I don't know if I've become harder to get along with or what. If not for clubs, I wouldn't have anyone to go on trips with.