Heh. The pain level in my lower back and hips dictates what I'm carrying at any given time.
Now, I'm not whining. I had a GREAT time getting in this bad of shape. Just recognizing that comfort's got to come first these days.
As such, the gun I have on me most often is the little Kahr 380 in my pocket. If the meds are working right, then one of the 640s, or either the 9 or 45 Shield, or even a K-frame if I'll be sitting more than standing. Point is, work with your situation, not against it. Something is always better than nothing. And so on.