This last fall I nearly started getting one of those obnoxious horses myself. It was starting to get cold and work didn't allow me to do a lot, if any, riding outside of fun shows. There were plenty of girls with those psychotic horses, and their parents ENCOURAGED that crap.
Before ANY run I made, I would make him STOP and stand for several seconds and stop and calm down before we would head for the gate to leave. He was just about as antsy to get OUT of the arena as he was to get in.
When I really realized what was happening I said that was it for the fall because I wasn't going to start getting that kind of horse and knew he needed MUCH more just fun riding instead of shows/speed.