A few months ago I noticed my horse hangs really heavily on my left rein when I take up contact. I'm not sure what I did that caused this habit, but I've been trying to fix it for a few months and I haven't really gotten anywhere. If anyone could provide any exercises I could try to help him I would love the feedback!
I work him on the ground for part of a warm up every day, I yield his quarters and forehand and try and loosen him up. He is much better on his left side on the ground than under saddle. Once I have him under saddle I do a lot of flexing and suppling on both sides, as well as lateral work. I do not think it's a question of him being stiff because of all these exercises that I do, so maybe it's something he needs to build muscle towards or maybe just a habit. He is also in a hackamore due to a mouth injury from a previous owner.
Thanks for any advice!