Currently 66 years old, as much as I try to deny it, age has an effect.
I don't have the strength that I did even 10 years ago, mostly due to a partial inability to weight train.
Way, way back, I dislocated my shoulder (IIRC at age 22) kayaking, then skiing, then skiing again, etc, etc, etc. Ortho doc said surgery was the only option, but delay it as long as possible due to long healing time and even longer recovery of strength and range of motion. He was right. I had the shoulder rebuilt six years later, just before I turned 30.
Shoulder was fine for 6 months, until I was run over by a pick up truck while bicycle commuting home from work. (my 4th year of bike commuting)...broke tib-fib on the left leg (think Theismann injury), fibula on right leg, broken pelvis, several broken ribs, broken left humerus, assorted lacerations and contusions, severe infections, many surgeries later I walked again, and returned to work after six months...but the shoulder was fine---for 30 years, until the joint just plain wore out.
I can still paddle and carry, and yes, I still ride a bicycle for fitness, as well as weight train as best I can. (no presses)
Have I adjusted to my aging, battered body? Well, sure I have, very gradually. I have reduced the challenge of some trips, mostly since I go solo.
There are some things that training and willpower cannot overcome, but that's OK. Slower is fine, as long as I can still go. Sleeping is tougher, I switched to a Hennessy Hammock. Carrying is a bit more effort, I got lighter gear. Trips too long? I'll shorten the mileage. Eventually, I know I'll not be able to compensate, and I may be forced into day trips only, but for now, I trudge along.
Some of you older warriors give me hope and inspiration, you've set the bar pretty high, and for that I thank you...