MAKE him listen. I just bought a new horse and I had to state my dominance. He was a submissive horse, but I put him on a lead rope and we would walk soooo slowly or quickly and do random stops. I'm the boss, I'm the leader. Then we worked on lunging. Make him change directions a lot, as soon as you ask. Lead him around again on a lunge line. As soon as he doesn't listen (looks outside, neighs to a friend, walks away, etc.), make his feet move. I backed my horse up, make him spin, just don't move forward. He will listen after that. Also, instead of free lunging, put him on a line.