When I was five, I was taking lessons from a Dutch dressage master. I was riding his big horses and I had little legs that were too small to do much. He had straps that went around your waist and attached you to the saddle. Mind you, this was the late 50's, so not too many contingency fee lawyers back then.
I shudder now thinking about that, but I got to ride piaffe when I was seven and didn't fall off!! Capt. Heyer was making the piaffe, not me.