Great suggestions so far. I would not have thought of many of them.
I didn't start riding until I was 58. I have improved until I am in much better shape at 65 than at 58, despite an electrical heart problem (to be fixed in August). I also lift a lot of weights, but don't find that the muscle mass slows me down
My wife and I ride together, but we don't compete. I don't compete with anyone but myself, and I find pleasure in my small (and big) improvements. Perhaps if he rode by himself at times. It is a great experience of "soul time."
Good luck.