Grain!! small amounts at first.
And lunging, round pen work.. doesn't have to be round.. a large paddock will work.
The key, don't let him put his butt towards you, you want his head/face/ears towards you.
When you let him stop, don't let him look out away from you, if he does, keep his feet moving, go a few times around one way, then reverse him
and have him go around the other way, he doesn't have to run, walking/trotting is fine.
when he faces towards you. STOP, step back away from the center of where you are standing, put down the stick/rope/ thing you are holding... and see if you can walk towards him.
Don't try to pet his face first, try for the neck, soft hi pitched voice.. let him sniff your hand.. try to pet the neck.. if not just stand there for a moment quietly.. then turn and walk away from him..
See if he will follow.. if not just let him stand for a moment or two..
Then ask him to move again.
The goal of this is to teach him, its easier to turn and face you, and its easier to hang out with you than being run around in circles...
IF you like to give treats.. (I do), when you stop for the first time and he is at least standing parallel to the fence, and his head is turned towards you. Put down your whip/stick/rope... and hold out some corn or other treat.. see if he will take it, or put it on the ground in front of him.. then walk away...
give him a moment of rest, then go back to lunging...
Just repeat the steps above, The goal is to have him follow you like a dog, or at least let you pet him and get him to want to be around you..
The reason you walk away, is to get him to acknowledge you as the leader and to want to follow you.
I hope this helps, you can find a lot of videos on you tube about lunging for respect and lunging to get the horse to "join up".
Carol