Thunderspark, that's what I'm asking in the post, what kind of exercises I should be doing with him. I just ordered the 101 groundwork exercises book, anyone have it/like it?
I think more than specific exercises, you just need to spend a lot of time doing things with him. For instance, halter and lead rope, practice leading him with his chin right at your shoulder and if he moves up or behind, stop and correct him gently. Brush him, and make sure he stands still for you. Start out short, 30 secs, 1 minute and as soon as he stands still for that short time, reward him with a treat or let him go. You can do a lot of tiny things that establish you as boss mare, without having everything be a struggle. Little things like, when you step into his stall or paddock stop just inside the gate and let him turn to face you. If he doesn't, then tap him on his hip with a stick or lunge whip, very lightly at first and increase your energy and force of the tap until he yields his hind end and faces you, then praise him to high Heaven. You can teach him to yield his hind end by using a lunge rope and whip. Halter him up, hook the lunge line on his halter at the chin ring, then walking slowly down his side toward his hip, walk around behind him so that the line is around his hip as you go to the opposite side. Start pulling toward you, lightly at first and stronger as needed, and finally give that hip a good yank toward you if you need to get him to move his feet. Do that a few times and pretty soon, light pressure on that hip and he'll move it real quick. Then you can progress to standing at his shoulder and tapping his hip with the whip, increasing your energy until he moves that hip, just one step. I call that "Hide your Hiney" and my horses learn that when I look at their hip and point or even say, "Hide your Hiney" I mean for them to turn and face me. That way you can always keep his feet moving (and if you can move his feet, in his mind you are the boss) and you can keep his backside away from you, so he can't kick you.
All these things, where you are telling him to move out of your space, put he backside away, face you like he would the lead stallion or mare, are telling him, "I'm in charge." and respect will follow. He'll probably challenge you but as long as you keep a whip or something to make him believe HE is what's for dinner tonight, he'll start backing down, quicker and quicker and challenging less and less.