When your groundwork is really good and your horse is of an age to
start or re-start, things should be pretty easy from here.
After the horse is used to having you work from "above" him on both sides,
try sliding on his back, balancing for a millimeter of a second, and sliding
off the opposite side. And again in reverse. Not only should your
horse be prepared for this, but you should be prepared also. Get yourself
in shape--practice balancing on a therapy ball, standing on one leg,
etc. to prepare for bareback.
Before you decide to "ride" your horse, please have a look at Dr. Deb
Bennett's website, Equine Studies Institute, and her
article about conformation, growth plate fusion, starting a horse, and gaits, entitled:
...did you ever wish your horse would "round up" a little better? Collect a little better? Respond to your leg by raising his back, coiling his loins, and getting his hindquarter up underneath him a little better? The young horse knows, by feel and by "instinct", that having a weight on his back puts him in physical jeopardy. I'm sure that all of you start your youngstock in the most humane and considerate way that you know how, and just because of that, I assure you that after a little while, your horse knows exactly what that saddle is and what that situation where you go to mount him means. And he loves you, and he is wiser than you are, so he allows this. But he does not allow it foolishly, against his deepest nature, which amounts to a command from the Creator that he must survive; so when your foot goes in that stirrup, he takes measures to protect himself.
The measures he takes are the same ones YOU would take in anticipation of a load coming onto your back: he stiffens or braces the muscles of his topline, and to help himself do that he may also brace his legs and hold his breath ("brace" his diaphragm). The earlier you choose to ride your horse, the more the animal will do this, and the more often you ride him young, the more you reinforce in his mind the necessity of responding to you in this way. So please - don't come crying to me when your 6 year old (that was started under saddle as a two year old) proves difficult to round up! (Not that I'm not gonna help you but GEEZ).
If he does not know how to move with his back muscles in release, he CANNOT round up!!
So - bottom line - if you are one of those who equates "starting" with "riding," then I guess you better not start your horse until he's four. That would be the old, traditional, worldwide view: introduce the horse to equipment (all kinds of equipment and situations) when he's two, crawl on and off of him at three, saddle him to begin riding him and teaching him to guide at four, start teaching him maneuvers or the basics of whatever job he's going to do - cavalletti or stops or something beyond trailing cattle - at five, and he's on the payroll at 6. The old Spanish way of bitting reflected this also, because the horse's teeth aren't mature (i.e., the tushes haven't come in and all the permanent teeth) until he's six either.
When I say "start" a horse I do NOT equate that with riding him. To start a young horse well is one of the finest tests (and proofs) of superior horsemanship. Anyone who does not know how to start a horse does not know how to finish one. The animal does not belong inside a fence or in a stall, and yet that's where he's gonna have to live and work. You, the owner, have the following as a minimum list of "things to accomplish" together with your young horse before he's four years old when you DO start him under saddle:
1. Comfortable being touched all over. COMFORTABLE not put-upon or tolerate, but comfortable as in man he really looks forward to it.
2. This includes interior of mouth, muzzle, jowls, ears, sheath/udder, tail, front feet and hind feet. Pick 'em up and they should be floppy.
3. Knows how to lead up. No fear; no drag in the feet.
4. Manners enough to lead at your shoulder, stop or go when he sees your body get ready to stop or go; if spooks does not jump toward or onto you, will not violate your space unless specifically invited to do so.
5. Leads through gate or into stall without charging.
6. Knows how to tie and knows what his options are when tied.
7. Ponies.
8. Carries smooth nonleverage bit in mouth. Lowers head and opens mouth when asked; bit can be removed without horse throwing his head up.
9. Will work with a drag (tarp, sack half filled with sand, light tire, or sledge and harness).
10. Mounts drum or sturdy stand with front feet.
11. Free longes - come when called and respond calmly to driving request - relaxed and eager.
12. When started, leaves without any sign of fleeing; when stopped, plants hind feet and coils loins - does not depend on your hand to stop him.
13. Familiar with being girthed; if necessary, allowing horse to work out any need to buck in pen at liberty.
