He’s letting you know where his thresholds are. Respect them. Start with the outdoor arena. Stop where he first hesitates. That’s a threshold. Don’t push him over it. Retreat and advance, and retreat and advance, again and again and again until he can move calmly past that threshold. Repeat this every time he hits a threshold, which may only be another foot away. You may not get very far at first. This is a process. It is not a physical thing, it is a mental thing. You have to get into his brain and his feet will follow. Horses are “prey animals” and they think that a horse-eating butterfly is going to kill them! By forcing him past his thresholds he is forced to internalize his fears and eventually could explode because he thinks he’s going to die. Every time he can walk calmly past one, you are building his confidence and he will put more trust in you that you are helping him to be safe. Horses don’t care how much you know until they know how much you care!