What exercises help a horse that wants to rush off in a fast trot?

When horses are keen to rush off, I find lateral exercises helpful. I usually start with leg-yield, riding up onto the quarter line, out to the outside track and back to the quarter line again. If you have a horse that quickly works the exercise out and tries to anticipate you, it helps to circle back once you reach the outside track the second time, and to keep varying how many times you move across.

It is also useful to keep in mind that as soon as you go up a tempo or change your line, you can use a few steps of leg-yield if the horse wants to rush forward. That stops you working backwards in the rein, which is easily done when you have a horse that wants to run away from you 😄