Stacie- Try a little reverse psychology on him (don't know if that's what it is called) or play on his soft side . My neice was about 1.5 yrs old and I put her up on my old mare for a little pony ride. Well she fell off. She was fine, but didn't want to get back on. Instead of forcing her or trying to talk her into it. I just said "Ahhh, poor Flame is sooo upset you fell off, poor girl." Before I knew if (literally like 20 seconds) she is hugging Flame and saying "poor Flame, I love you" etc, etc. Then she got right back on and rode around again. I was actually riding with her later that summer and the horse tripped & fell. We went down (I twisted her around so she didn't get hurt), but she got back on. I was so proud!
No she is 4.5 and as brave as anything. The horse spooks/jumps a little bit and she doesn't freak out or anything. Its great
I have someone to pass the riding on too.
Sorry for the book.