When my friend David (who also happens to care for our horse's feet with great expertise) bought this mare (a Paso Fino), she had been living in a show barn and had been pretty badly mistreated. As a result, she had developed some dangerous behavior as a defense mechanism against the abuse she suffered. Rearing, bucking, bolting, kicking, biting... you name it, she did it. David told me that one day she reared up and flipped herself over on her back in a protest against being handled. Using Natural Horsemanship techniques, David was able to gain her trust and teach her new skills and re build a good life for her.
Today, she is as gentle as a lamb, and so sensitive to every slight movement of her handler/rider.
David has taught her to lie down on command, which displays her compete trust in him.
She also lets David stand on her back. I think he usually does this with a saddle; so his boots don't hurt her back. He did this briefly as a demo on this day.