My early pony riding lessons were all about controlling naughty ponies and riding them without stirrups and / or reigns while trying to make them canter nicely 3/4 of the arena instead of taking the shortest way to the next pony in a nice gallop LOL This helped me the most to keep my balance and develop a steady seat then any dressage. Further I did some riding in my early twenties and got me a book about a type of riding that opened my eyes regarding the rider's seat. It explained how your pelvic should be slightly rotated to absorb the movements of the horses back while riding. It learned me how to actually sit through a gallop instead of the English way, which would allow the horse to use it's hind legs (the motor of the horse) better with less change of tripping over forward, because most of the weight of a horse is on its front legs already. It's what the cowboy's seem to do when galloping too. Since you have some back problems, I might explain it to you by PM if you like. It takes a little time to make this position of the pelvis a habit but if you try it out you will feel it works immediately, at least I did. I could scan the illustration that goes with the explanation in the book for you.
I hope to be able to do some natural horsemanship riding some day, looking back at my years of riding the regular way, I feel slightly bad about myself doing some unnecessary stuff that the horse I was on probably did not like or deserve, just because I did not know better and / or was told so by others.
