My suggestion, if you can't hire someone, is to get some form of Natural Horsemanship Training DVDs and start moving his behind. I like Clinton Anderson. Other people prefer other instructors. It doesn't matter who you choose as long as you learn the concept of making his feet move immediately when you say to move. Make him think he is going to die if he doesn't do what you say. He gets pushy, you make him move hard and fast. Back him up and put the fear of you in him.
If you watch a herd, the dominant horse will pull back their ears, snake their heads and then if the other horse doesn't move, they will attack by either trying to bite or kicking at them. This is how a horse learns who is boss. You don't have to cause damage, just make him think that you will if he tries any crap with you.
Imagining life without a horse is like imagining life without food, water and air.