(“See if he is willing to continue on”)
I want you to do me two favors the next time you are schooling your horse on the flat. First, whatever you’re doing — trotting down the long side, leg yielding on the diagonal, whatever —briefly stop using your aids and see if he is willing to continue on without your constant prodding. Don’t expect him to go on forever. He’ll need to be reminded of his duties, but you would like him to carry on without the need to be nagged incessantly. “Self carriage” is more than holding his head up without leaning. It’s your horse’s “willingness to carry himself forward”—his whole body. If you never give him a chance to try it, he’ll never figure out that he can (or should).
Now about that other favor …. As you are riding, consciously decide how “sincere” his movement is. Are his reactions casual, perfunctory, lackluster, thoughtless? It’s not just what he does but why and how much he is thinking about them. Or, hopefully, does he feel motivated, dedicated, involved? This is a difficult awareness to acquire. Once you have felt it, the feeling is unmistakable. The difficulty is if you have not felt it, sometimes you might think you have and never look further. This whole question is one which you should roll around in your mind fairly often as you think of your relationship with your horse.