My coach has been very into one exercise at the moment and it is 3 trot poles into and x of poles then one after you can then leave it at that or pop some jumps up with the poles it is a good exercise to make you and the horse think and definitely helps with straightness if that is an issue
Hope this helps
Check out a horsephysio channel on you tube ☺️💚 Good Luck!🍀👍
Something like what's in the video is a very difficult grid if you're up for a challenge!
I also borrowed this from pininterest but it's an interesting concept for something a bit different