When mounted up on a trail ride, teach your horse to stand still until you give a cue to move with this technique from top trainer/clinician Julie Goodnight. http://trailridermag.com/article/stand-still-and-chill-15644
Is your horse “jiggy” and tense on the trail? Does he trot anxiously in place, refusing to move forward slowly and calmly? If so, you’re likely tense and worried that he’ll take off if you