Okay, now for my story. =o I'll try and make it short.
A year ago I finally was able to financially support my horse (he lived with my dad about 800 miles away....divorced parents) and brought him down. Long story short, my horse is the opposite of yours. He is a monster out on trails. He is horribly barn sour, randomly gets hyped up (he doesn't spook but will build up energy until he explodes) and I imagine I tense/have tensed up when I'm in a more dangerous situation (on the road/around cars/next to rough terrain/cliffs) and he swings himself into what ever I'm telling him to stay away from.
Now all of that is normal and expect, what I didn't expect was for him to get worse overtime. I thought more trail riding and he would eventually calm down. Well it just got worse, he started rearing and leaping vertically into the air. He would jump into anything or anyone. He tackled several horses (with riders), caused eye trauma from launching into a fence, would jump into the river crossing. I could not keep this horses front feet on the ground, he would canter in place, and rear every two steps. Once this started his arena work went to crap. He wouldn't canter consistently. If he had any bit pressure he would throw himself into the bit, slide to a stop and do several mini rears. I was at my mental limit, trainers were baffled, and vets found no pain. He fought everything I did, my soft mouthed horse spent 70% of every ride pulling as hard as he could against the bit, giving himself cuts and I had severe rope burn on both my hands.
Then he fell once while rearing, I managed to jump off easily. But was giving up on me, once he fell it took me about 10 minutes to convince him to get back up. A week later he had done this 3 times. At the end of the week he threw himself over backwards with no warning, was very very lucky and escaped being landed on by inches.
It was then that I wanted to give up, I had good reasons to. He was a danger to himself and anyone around him. Honestly, I don't know why I considered to keep riding but I did.
I gave him two weeks off, moreover myself two weeks off. Then restarted him, worked on ground work then moved to riding in a halter. Now he hasn't reared out of frustration/on trail in 4 months. He is doing lovely in the arena as well. Jake and I are probably horrible for each other, we know how to piss each other off and bicker between us. =) But in the end we somehow get the job done.
Its hard and it takes time, try playing games in the arena instead of working. Try working on teaching things slowly instead of just going in circles, work on leg cues, turns on the hind and fore....and so on. Keep it light and fun.