I do an exercise all the time with just poles to help my mare be adjustable. Sometimes I do it 3-4 rides per week.
Set up 3 poles in a straight line, each pole 45 feet apart. First trot through them focusing on balance. Then canter in making 4 strides between each pole. If she is running through you, halt in the middle, they are just poles so you can even halt over the top of them. The key is to not be hanging on the horse. It may be hard at first bc 45 ft is a short 3stride. As soon as she lands off of a pole say whoa really loud with your thigh and hand -dont literally say it! You want to make sure you are in a place where you can put your leg on in front of the pole or jump so its important to half halt early.
Once you master cantering through in 4 strides to 4 strides, you can start doing 3 strides to 3 strides. Once you master that, you can start making the middle pole a jump.
I hope this helps, it improves my horses adjustability a lot, hopefully I explained it well enough that you understand it, let me know if you have any questions !
Gypsy & Scout <3Everybody is a genius. But if you judge a fish by its ability to climb a tree it will live its whole life believing that it is stupid. ~Albert Einstein