From about ten through my forties, push-ups were not something I mastered, they were something I did. Starting at some point over 50, something in one shoulder

From about ten through my forties, push-ups were not something I mastered, they were something I did. Starting at some point over 50, something in one shoulder really, really objects to pushups. I wish it were not so, but I'm not sure it's worth exhaustively researching.