Instead of tying your horse just run your rope around a stout pole or post. Keep your lunge whip handy in your right hand and the lead in your left. The only reason you have the lead is to prevent a wreck. As soon as he starts to pull, hang on hard to the rope and tap his hip over,ie, get his butt moving and make him hustle. This gives them something else to do besides pull. Move to his other side and do the same. Be sure to stop when he stops and stands quietly. A treat at this time might go a long way. Be patient and be prepared to wait there with him. As you do, turn your back on him. If he thinks you aren't paying attention he may try again. This does work as you are giving him a choice-it's his decision to move or stand quietly.