No rider should give up and get used to a horse weighing in the hand, stiff, uneven, doing bad transitions, or unable to perform a certain exercice. You just have to teach your horse to use his topline correctly and focus on keeping him balanced.

Whatever breed your horse might be, or whatever difficulties you might have with him, I can train him on a regular basis and school him up to 4th level... and why not above ? Wether you are interested by competing or not, or even if dressage is not your main preocupation on a horse, you should be able to exercise your horse with suppleness oriented movements, as basics as lateral works, and idealy, as tonifying as a school trot, a light piaffe or flying changes. Dressage is for every horse and is the best way to keep him fit and sound throughout his life.
It's also a very deep way to communicate precisly with you horse and share with him the pleasure of learning.

Going slowly but being firm about what i expect is the key to establish a simple and understandable dialog with your horse.
I also like to bring some diversity with exercises on the lunge line, long-reins, liberty, or going to work on the trail.