Loading Hershey

About a week and a half ago my mom and I went out to try to load Hershey in to our new horse trailer by ourselves for the first time to take him to my lessons....... Not very good results, we did exactly what the lady we got him from told us to do, but I think Hershey thought we were boring, because when we lead him up to the trailer and asked him to go in, he just planted his feet and fell asleep! I  tugged and pulled, ( which I learned never to do because it's like playing tug of war with a giant! ) and even tried to tempt him with treats and hay, but he just looked at me for a moment and fell asleep again! If I could read his thoughts, I bet he would be thinking this,( gosh you people! Do you really think I'm going to get into that little moving box? I don't think so, I'll just fall asleep until you give up.) After about 45 minutes of unsuccessful attempts, we gave up and called my riding instructor to tell her we could not get Hershey into the trailer and we wouldn't be coming to lessons, we were already late anyway. My riding instructor told us she had been waiting for this call. she came out a few days later to help us load him, what she had me do was work Hershey a lot, like lunging, backing, going over things, ect. Then I would back him over to the trailer and have him face it with the doors open, what this is supposed to do is have Hershey learn that away from the trailer is work but by the trailer is rest, I did this a few times then we tried to load him, he did pretty good with getting his front feet in but he always tried to step back out, and when he did this my riding instructor would raise up a whip behind him (not hit him) so he could see it and if he still tried to get out she would tap him on his behind and he would get right in! My mom and I  tried this a few more times and he did really good.