I'm 66 and have been a CHL holder for about 8 years. I have a few back issues but otherwise don't feel much more beat-up than I did in my 40s. Still ride my Harley hundreds of miles in a day, still love to be outdoors and still love shooting, work out with weights several times a week and walk two miles a day with my dog (get a dog, they will force you to get out and get your heart pumping).
Age affects everyone differently; I have no arthritis problems, strengthen my grip every day with a GripMaster and practice hard at the range. Physical problems teach you to work around them as best you can; there's no reason to stop shooting because you're not 25 anymore. Armed old-timers are a great resource ...
"The welfare of humanity is always the alibi of tyrants." Albert Camus