Some people I've worked with in the past would also take short trips after they got the horse on the trailer. They would start by going around the block and eventually they would go to a nearby quarry to walk around and come home. One lady would even sit for a good 1/2 hour or more and let her horse eat hay. She had run into a problem when she first started. She would put him in and then take him out, he was a smarty and got it in his mind that once he went in he could fly out and then expect a reward. Good luck.