Originally Posted by DraftyAiresMum
That's not called being bombproof. That's called not giving a **** about what you say and thinking his in charge. In a phrase: he doesn't respect you.
Any time he gets "a little cheeky", get after his butt and make him think it's the end of the world. Shank him back if you have to, smack him on the chest with the lead rope or a dressage whip or crop (not tap, SMACK, make him move his feet. YOU are the boss, not him. Right now, you're nothing to him but another horse (albeit a two-legged one) that he can walk all over and treat any way he wants. Watch a herd interacting. If he tried acting the way he acts with you toward a more dominant horse in the herd, he'd get his a$$ handed to him. You need to do the same thing.
Disrespect in ANY form is NEVER okay. That's how people get hurt.
I dealt with this same problem with my young mare when she was 3. I'm a fairly small person (5'3" around 125lbs) & she's a big gal (well much bigger than me). She used to always push her weight around into me & would drag me across the arena. She scared me. One day I got fed up with it, pulled out the lead chain & haven't had an issue since. I don't normally
advocate using stud chains, but with extreme cases I do. My mare responded AMAZINGLY to the chain & I've never had to bring it out after that one day working in it (I've probably brought it out ONCE since then because she was being an absolute brat with my barn rat & grandpa - I'm away at school so can't work her frequently).
This mare is now extremely respectful of my space. I teach all my horses to back up when I squeeze their shoulder & walk towards them. This mare? All I have to do is motion with my hand at her chest & walk towards her. She FLIES backwards. I would not advise using a stud chain if you've never used one before. I would find a trainer or friend who's used one before because like any stern equipment they can be destructive if used wrong.