some things you can work on are teaching him to put his foot in a bucket of cold water and stand with it in there.
teach him to walk with a leadrope attached to his halter, dragging on the ground, and let him step on it and figure out how to deal with that. (do this initially with a relatively short lead and in a round pen or smaller paddock)
practice wrapping him in polo wraps .
practice giving him wormer . use a syringe with applesauce in it.
get him really good at taking a bit, and releasing it.
work on getting him to allow you to put your hands in his mouth, and inside his ears.
some of these things may come in handy if you ever have to "doctor" your horse.