Add this to your carrot stretches a couple of times a week. Hold a carrot piece between your horse’s front legs so he has to stretch his head, neck and back to get to it. Start with the carrot at his knees. As he becomes more flexible, hold the carrot further down and then further back between his legs. After a month of doing the carrot stretches and this cat stretch, see if you can get him to stretch far enough to actually rock back slightly onto his hind end. Always end your stretches with one minute of good scratching to reward his effort.
Home Horse Riding and Training Natural Horsemanship Cat Stretch
by tapping his elbow before putting the carrot between front legs , i teach him to bow his head on command
I taught my horse to bow with a treat like this too.