Here is some stuff I''m going to try to get my horse accustomed to quick movements - I read about a team of Texas Policemen who use these games to get their horses ready to do crowd control:
1. Exercise ball soccer. Start out just u & the horse pushing the ball around. When the horse follows it with his nose on a lead line, praise him - show him through release & reward what u expect him to do. Work up to his pushing it about with his front feet. Wrok on this from the ground until he is very comfortable with it, then get on & ask him to move the ball about the arena. Later, having other friends teach their horses the same thing & u can play the game with another horse & rider.
2. Broom polo - pretty much the same process using a broom to hit a ball around - like those cheap KMart colored balls about the size of a basketball. Work from the ground again so he is comfortable with the broom moving about & the ball. Get him so he will go after the ball for you. Then work around him all over swinging the broom until he stands as if bored by it. then get on, practice swinging the brooom to get him used to it, then actually hit the ball with it - same thing, friends learning can become a game between two teams.
3. Nerf football is about he same thing - people throw the ball around the horse while on the ground & graduate to tossing it via horseback.
4. There is other nerf games u can play with the horse so the objects wo not hurt.
You must be careful & do these things though without making the horse become afraid if he is not afraid now.
Maybe before these u wish to do something more basic - like getting the horse to put either front or hind feet in a hula hoop laying on the ground - practice placing all 4 of the horses, feet exactly where u want them - this could be an endless game used all winter until you're a pro. The horse will not get bored as long as u are:
1. Asking in a manner he can understand
2. Asking using small expectations - mvoing hind quarters toward the hoop is the first step, then reward.
3. Rewarding immeidately at the slightest try & not asking for more until he is got the last step down.
4. Ending each session on a good note- never ask him to do the next level & quit in the middle without success - if you're having a rough time getting what u want, go back to the last step that was successful, perform it, praise, reward & quit. A horse will think about what he is done that day over night & remember it the next session.
5. when he is got it down, do not repeat it over & over & over & over - that is boring, challenge him with the next thing that is different.
Have fun, good luck!