Could he maybe take some online exercise classes, like from SilverSneakers?

He wouldn't have to actually do anything, just watch. I bet it would motivate him to follow along, bit by bit. It works for me, anyway.

For music, does he listen to the same favorites, over and over, or is he looking for unfamiliar works? I ask because on Amazon digital music, there are anthologies of concertos (piano / violin) of literally dozens of works, by lesser-known composers. Lots of great music, hours and hours, for just a few bucks.

It might spark his curiosity to explore more. Just a thought.