What I wouldn't suggest you do is getting a stronger bit or lunge him until he tires out. First try to find the reason for his behavior. Is it the weather, is he spooking at something, does he go out to the pasture 24/7 or is he cooped up in his stall, or does he anticipate? You first have to find the root of the problem in order to fix it, and not try to find a temporary solution. Maybe you could try doing more flat work, liberty etc. This could help him trust and respect you more and actually listen to you and do what you ask of him. But remember, in order for him to listen to you, you also have to listen to him.