But I can't get him to break out of the walk into a trot (or gait - he does both).
I've tried just increasing my walk speed, and he just walks faster until he starts dropping behind me, then raises his head and fights it. I've tried jogging off, and he just holds his previous speed, then raises his head when I get to the end of the rope. I've tried holding the end of the lead rope or a dressage whip in my left hand, flicking him lightly as I speed up and he doesn't match me, and he just swings his hind end away from me and comes to a full stop.
When I bought him and had the vet check on him, he had to have someone chasing after him with a crop, which sort of worked, but I don't consistently have someone around to help (I usually go out in the evenings after work, and often am the only person there).
What's the best approach from here? Should I just work on continuing to change my speed up and down, getting a little faster each time until he gives in and breaks out of a walk? Or should I only work on it on weekends when I can enlist the help of a friend with a crop? Any other approaches that I'm missing?