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 gun has been called the great equalizer ... It insures that the people are the equal of their government whenever that government forgets that it is servant and not master of the governed." --Ronald Reagan