By building the confidence, then they will have exceptance, which will give them understanding, that will produce results. Lee was still on horse back and started moving the filly around. This is how horses control each other. The horse that moves the horse around is the leader. This is how to get respect.
Some aggressive horses are insecure.
They will usually look to a dependable gelding in the herd when something comes up. All horses are looking for leaders. Lee likes to ride with a bull whip and she uses it to help desensitize. When the horse would face up to her, Lee would ride away to give the release. Then she would start moving the filly around to prove to the filly that she can control her motion.