I carry rarely and there are many good pistol recommendations in this thread than I can't improve. There is one critical recommendation, however, that needs to be added for all of us "old folks" and that is EXERCISE! When I was in my early sixties I had all kinds of aches and pains and my balance was a little off - I was getting the symptoms of "old" . My doctor suggested exercise and walking. Now at age 72 and after about ten years of frequent exercise, I have no serious joint pain, I don't get winded, and my reflexes are good.
Additionally, for hand gun shooting, I have one of those hand grip squeeze things in the car that I squeeze (ten reps) periodically while driving around town. I exercise both hands. My weak hand is stronger and my trigger control on both hands is improved. I can't crack walnuts but I can easily rack all my semi-autos and I can comfortably shoot full boat .357s out of my 640 J frame and I can shoot my Dan Wesson 44 at arms length (bulls eye style) without quivering.
I agree. I'll be 71 in July and try to exercise 3 times a week. Mostly cardio(bicycle, elliptical stepper, treadmill) and relatively light free weights. A man could hurt himself throwing heavy iron around. I don't say I have no aches and pains but they are minor. I've been lucky to not have serious health problems and the exercise is mostly to stave off as many problems as I can.
I carry a model 65 w/3"bbl that has had an action job and the hammer bobbed for DAO. I'm still not a great shot but I can hold them on a paper plate at 15 yards double action. At 6'1" 205lbs, I don't notice the weight too much. A good belt helps.
The original poster asked a very pertinent question and has been given many good answers to choose from. I have a feeling that there are others reading this that don't have the physical limitations but still don't want to carry a full size 1911.