60 here. I was avid backpacker in my youth, and though I still work, have returned. I backpack, kayak-camp and fish, fish backpack, and snowshoe camp.
Last Feb I had a stent put in which solved a problem of pain and shortness of breath I thought was due to age, now I'm full speed again. My pace has slowed a bit because I enjoy rambling and taking in the sights. My comfort zone is the wilderness. Desert, mountain, no matter. I will never give it up. I am as comfortable with a 50 lb pack as I ever was, though do try to lighten a bit.
So - trek on ye aged!
My idol of sorts was Colin Fletcher - sad his passing. I have most of his books.