I agree with what some people have posted about working near the gate. If that is where your horse wants to be, make him work really hard while he is there. Do roll backs, circles, whatever you want. Just make him work. Once he gets a little tired and looking for a rest, go to the opposite side of the arena or where he doesn't really wont to be and let him rest. You will probably need to repeat this several times every time you ride before he gets it. Also, like many people have said, make sure he doesn't get to associate the gate with rest. When your done riding, get off and loosen his girt, take off leg wraps, and take off the bridle away from the gate. Basically, once you firmly associate the gate with work and not rest, he will no longer want to be there.