There are several threads on Brian Enos' website about this very issue. For the joints, aches and pains, you can do the typical stretching, physical therapy, and of course NSAIDS. I have arthritis in both hands. Celebrex helps a lot, but I hate putting chemicals in my body. I also have surgically altered shoulders from previous traumatic injuries, and both of my elbows have been scoped for chips. The tendonitis in my right elbow is on both sides, golfer's elbow and tennis elbow. In my left elbow I have tennis elbow. I have a chioce, cowboy up or quit. My doctor wants me to quit. I am sellling my open division gun this week and replacing it with a heavier, softer shooting, gun. I no longer shoot magnum calibers at all. Do what you gotta do.
For the vision issues, I quit shooting precision pistol games and went into practical pistol where the distances are much shorter. In IDPA or IPSC, an aging shooter can do very well with a softer sight focus. For steel challenge shooting I went to an optical sight. Of course, the young pups are also shooting optics at warp drive, but that's ok because shooting an optical sight makes it more enjoyable and this is about fun. Shooters who need the sharp sight picture as in PPC, find an eye doctor who will work with them. Many guys have prescription glasses made specifically for their game be it trap and skeet, or bullseye. Arrange to take a firearm with you for your next exam and you ill be amazed hat a shooting sports oriented optometrist can do for you.
Aches, pains, half blind and all, a senior shooter can do ok on the stand in one spot and blast away practical shooting events. That's one reason cowboy action has attracted so many seniors. Of course, the field courses kick my butt because I am fat, lack flexibility, and I am not athletic. That is more a result of overall physical condition than age. But face it, given equal shooting ability, the more physically adept shooter will win an IPSC field course everytime. You just need to set realistic goals and never say die.
There are some things you can do to help prevent some of the problems associated with shooting but from your username (41mag) you might not embrace what I chose as a course of action. I quit shooting all long range handgun events altogether. No more chickens, pigs, turkeys and rams. I don't even own a magnum caliber anymore.