Groundwork, groundwork, groundwork! If you have a roundpen (not required, but certainly useful) put him on a lunge line and I would suggest a lunge whip as well. MAKE him move, show him who is boss. He is clearly not the type you can "baby" into doing anything. (you shouldn't with any horse, really) He will only get worse and will have little to no respect for you. I'm not kidding when I say show him who is boss. If he wants to walk at first, fine. But the moment YOU want him to speed up or do what you want, make it CLEAR and do NOT let him push you around. Groundwork is essential. My horse was the same way. Sweet, but pushy and VERY temperamental. I worked his butt off lunging and now have a horse that respects me, doesn't run me over when walking, WAY better behaved when being ridden. I think your boy needs a little motivation. I also think that you should try the lunging first and then lessons before you sell. Things like this can take some time. I wish you the best of luck, he is absolutely stunning!