If he's in good shape, I'd leave things as they are. My cat is 13 this year, I occasionally buy him senior food, but usually it's just the adult stuff. If you want to give him a supplement for his joints as you would an older horse, then Cortaflex canine is good
The truth is, I'd rather be with my horses than with most people. I'd rather scrub buckets than scrub dishes. I'd rather go to a tack shop than go to a shopping mall. I'd Rather clean a stall than clean my house, and I much prefer horse sh** to BULLSH**..