What goes through your mind while you're riding? If you're like many of my students and clients, you are focused on not letting things go wrong. "I hope Spooky McJumpypants doesn't freak out in the corner" "I hope Ol' Twobyfour doesn't brace through this transition" "Hopefully Mexican Jumping Beans isn't going to buck today" This kind of thinking can be a self defeating prophecy. It's amazing how in tune our horses are to our mental state of being. They're just trotting along or whathaveyou, when they feel your body tense as you think about where they might buck/spook/swerve/brace or otherwise booger around. So your horse is thinking, "Well, shoot! Miss Rider Lady is really nervous about something that's coming up, I should be too!" We unintentionally clutter the horse's mind and make it more difficult for them to focus on the job at hand.
I was watching a boarder at my barn ride her beautiful black mare the other night. As they were going around I heard her say something along the lines of "stop bracing" to her horse... who continued to brace. Even though she was riding the horse in a way to correct the error, the horse continued leaning on the reins. When she changed her tune and asked the horse to be soft, the change was almost instantaneous.
Next time you ride, try it. Make a note of the negative thoughts that you have, and see what happens if you turn them around into a positive. It's not a magic trick, your horse won't suddenly learn how to do flying changes; and we can't change our horse's natural way of going or temperment. However, it's amazing how well a horse will work when we get out of their way.