I agree with JDI. You also need to think about how fast you do things....if you do things too fast you can really burn a horse out and make them completely sour to jumping. If you push, the horse will only give you so much jump. If you teach him and put a wonderful foundation on him and really prepare him, mentally emotionally and physically, he will jump his heart out.
Also, some horses like jumping, but they aren't suited for the sport. If he doesn't seem to be a jumper, don't force him to be a jumper.