If he is flighty, desensitize, desensitize, desensitize!! Horses tell you what they need when it comes to training. If he is spooky/flighty, he is telling you, "Hey trainer, I need you to show me more scary things to get me quiet!" If he's lazy and not afraid of anything, he is saying, "Hey trainer, I need you to do more sensitizing. I need more transitions and more 'move now' exercises!" Figure out of good desensitize/sensitize ratio for him. :)