If your horse’s walk tends to be lateral, try one of these two things:
1.Slow the tempo down. Just be sure your horse stays reactive to light driving aids in the slower walk. He shouldn’t get lazy or fall behind your leg.
2. Step slightly sideways. That will break up the legs on the same side so he can step more deliberately with each leg. With a young horse, do a bit of leg yielding. If your horse has more education, do shoulder-fore or shoulder-in.
This tip is excerpted from The Happy Horse Course. For more info on how to train a happy horse, go to: http://www.janesavoie.com/happyhorse/