I've been riding my friends little Thoroughbred mare recently because she can't ride and doesn't want her horse to sit for a year, and this mare is super fast. (She has never been raced either!) Her trot and canter are too fast, she does not respond to half halts, she's all go and no woah. She doesn't exactly stop with rein contact she just likes to throw her head. Her owner has a technique that works with her half seat but I ride western and don't plan on sitting that way the whole time. My question is what should I try to slow this girl down? My thought was do some circles but she can do fast tiny circles with those tiny legs of hers, it's crazy. I'd like to get her to be a nice calm (and NORMAL) riding horse when the owner can get back on. She'll probably only be ridden 2-3 times a week because I have 2 of my own mares to ride as well. Another boarder might ride as well so i'd like to share techniques that work.
Please help! :)