Delete, EVERYTIME you are leading your horse somewhere and you stop you should stand him up. leading from the barn to pasture, stand him up - leading from stall to crossties, stand him up - leading from crossties to arena, stand him up....... and so on, you get the idea. What will happen over a few weeks is your horse will learn that every time he stops you expect him to be square and at first it will be a lot of tooing and froing but soon he will work out that if you say stop that means he MUST stand up straight away and in the end that makes a much prettier picture for in the ring. Think of it this way, who would you put first out of someone who spent 5 seconds to set their horse or the one that was ready the second they stoped........