I think you may have stolen my paint horse. Your gelding sounds JUST like him. I'll share my tips for how we got over 'X-treme' laziness.
Alright, first off, like I usually advise, put him in a snaffle or that part twisted wire-part smooth that I mentioned before (In this case, I think it will help him a LOT). He needs to learn how to back up off of a light cue, so that when you go to show and put on your show bit (a tom thumb or what not) he'll be EXTRA responsive, and you'll use so little pressure it won't look like you're doing a thing. (I actually work my horses in a rope-halter-hackamore sometimes, but it's the same idea). To get a horse more responsive, you have to go back to things that create less pressure so they learn the correct response; using something that causes a little bit more pain just teaches them to become duller (as you may have found). Putting a stronger bit in his mouth WILL work, but only until he learns to become dull to that as well.
First and foremost, we have to establish forward motion. You're going to have to ignore his head and his speed; we also don't want him throwing his head up anywhere crazy, so you could put a martingale on him LOOSELY just so that he can't throw his head up to kingdom come. I mean loose--the only thing it should restrict him from doing is stargazing. He's going to need the freedom of his neck to work on his hind end and really get moving, like you're going to ask him.
Now that we're outfitted correctly (
), let's get the ball rolling. We'll start at the walk, because what I'll lay out here carries over to everything else.
From a halt, ask him to walk. You're going to ask him the way you'd like to ask any other horse (With my lazy horse, I breath 'up' and bring up my energy and chest, and lightly lightly Liiightly hug his sides with my calves, and I may click or say 'walk'). If he's as lazy as you mentioned, he's just going to stand there with a 'wtf?' look on his face. SO. Since you asked nicely and politely and he didn't listen (give him about one or two seconds to respond) you get to 'beat the crap out of him'. Take your spurs and really make him go somewhere. Leave his head alone, heck, if he trots, that's even better. The main point is, you need to use enough force to get him to move out of there--if he runs away, great! If he goes any faster then a walk, just pull him down very gently, and give him a pat--hey, he went somewhere. For lazy horses, that's a feat all on its own, LOL. If he starts to 'suck back' like you mentioned (he rocks backwards and slows down, rather then speeds up) do NOT stop until he jumps forward again. DON'T stop kicking/spurring/whatever it is you do until he goes forward! Stopping because 'its not working' just teaches him that sucking back was the correct response.
After you let him walk about 10-20 steps (he needs to go this far to understand that you really did want the walk), ask him to stop. Just like before, ask him the way that you would like to ask him when he is 'responsive' (with my horse, I sit deep in the saddle, say 'whoa', and give him the rein to encourage him to use his hind end and not lean into the reins). He has to stop when you give him the cues--not five strides after. If he ignores your light cues (my guess is he will), pull him to a stop and back him up, at least five strides. Important notes about the back up and stop:
1. Don't pull him to a stop harshly. If you yank back in 'punishment', his head is going to fly up. Then, every time you ask him to stop he's going to get scared, throw his head up, and possibly not even think about stopping at all because he's focusing on the yank.
2. When you back up, you ask lightly-- pick up the reins and give them a light, gentle pull backwards and say 'back' (or whatever it is you use). If he gives you a step, or four, or five and decides to stop, DON'T, I repeat, DO NOT, give a little squeeze to encourage him to keep going. This is a MAJOR flaw that many, many many people do. What ends up happening is you have to squeeze a little bit every couple of strides, then a little bit EVERY stride, and sooner or later your ripping your arms off to back your horse up. If he decides to stop backing and you didn't tell him to, get after him--give little jerks to get him to back up quickly, pull your feet up and knock him in the shoulder with your heels--something to get him to back up and do it immediately. Once he does that, let him stop for a moment, and once again, pick the reins up slowly, and ask him 'politely' again. If he doesn't listen, get after him. (You may have to work on the back up separately... if you want, I could get a video of me demonstrating it on my paint... It's something that's very important!)
Alright, So! You've asked him to stop, backed him up--now you're going to want to immediately spin him or turn him on the forehand. You want this to be way, way harder then him just stopping when you asked! But again, don't punish--just get the job done.
After that, stop him and let him take a bit to think, and let him realize that stopping is a good thing (he doesn't have to go anywhere). Then, asking him 'politely' to walk again, following the same steps as before. There's a trend here that applies to everything--ask lightly, then immediately get after him as hard as possible if he doesn't respond to the light cue. This is very, very important. Usually people make the horse lazier then he really is, and it's really very simple to do. When you ask a horse to trot, and he decides he doesn't want to right away, and then you nudge him and he just walks a little faster, and then you nudge him again a little harder and he walks a little more faster, and then you finally use spur to get him going, you are making him dull. The horse is thinking, 'man, I'm going to wait until she uses that spur because I really don't feel like going.' All those steps in between really don't bother him. What you want to do is give him the option--you can be very, very polite and light (if a horse can feel a fly on it's leg, he can feel you breathing differently in the saddle), or you can make his job very very difficult and a /lot/ harder. The secret is asking light and polite the first time, EVERY time, another thing people don't do. If they know the horse is lazy, when they go to trot they just end up spurring him and driving him out. The horse never learns to be light that way. If you are polite every time, and make him work hard immediately if he doesn't listen, he will improve. Sometimes, just doing these exercises at the walk can make a huge difference!
But, since your horse sounds super-lazy, I'm sure you're going to need to do more.
Now that he's beginning to get the idea, at the walk you're going to give your 'light and polite' cues, as I call them, to tell him to trot. Same deal, here--if he doesn't listen (or worse, sucks back) get him moving--I don't care where, or how fast. If he canters, just pull him down to a trot and give him a pat--once again, reward the forward thinking. He only gets about a stride or two to respond, so make sure you get after him quickly if he doesn't listen!
Once he does trot, let him go where ever he wants to go (this works well for lazy horses!) He can move anywhere in the arena, just as long as he stays trotting, and trotting with impulsion! If he tries to slow down to a walk, this is going to be hard. LET HIM. Once he slows down and breaks gait, get after him again and get him trotting, not jogging.
If it feels like he's going to slow down to a walk and you encourage him forward to maintain gait, it's not his responsibility to maintain the gait anymore--it becomes YOUR job. It makes the horse dull. In a show it's fine to do it (don't want to break gait in a class!) but at home, let him come down to a walk. Then spur him like hell back into a good, impulsive trot. He needs to do the WRONG thing to learn that it is much, much easier to do the right one. In this case, you don't ask him to trot politely... because you never asked him to slow down in the first place!
Now from the trot, again use your new and improved light cues to ask him to stop. Once again, if he doesn't listen as soon as you ask (give him a chance, but don't draw it out), you know what to do! It is important to note, if you horse ever does present you with a really nice, pretty stop, back him a step or two, praise the CRAP out of him, and let him sit there for at least a full minute, more if you feel like it. He needs to know that if he stops well and cleanly, he's going to get rewarded! If he stops poorly, of course, make him work for it, then see if you can get a quality stop to show him that it's easier for both parties, lol.
Hopefully he'll be walking and trotting on command, so now it's time to tackle the lope, which I handle a little differently. (Man, I am really writing a book today, but I think it will help!) Now that he's trotting with impulsion (a nice rhythm, a hunter-under-saddle trot, but not quick and crappy and out of control), give your cues for the canter (push his hip into the center of the arena, pick up your inside rein, breath up and bring up your energy, kiss and use your outside leg... well, that's how I do it ^^). As usual, I'm sure he'll go Super-Lazy on you and just start trotting faster. But that's not what you asked him, right? Pull him back into your comfy trot, and ask again--but this time, get the canter. I don't care if he gallops, if his head goes into the clouds, but he has to learn that when you ask, he listens and the world is a happier place, lol.
This is another gait where for a day or two, if you have the resources, you can let him canter wherever he wants to go. DON'T worry about his speed. If he's a lazy horse, it's not going to be hard to get him to go slow. Just push him out--a horse can NOT collect and go slow if he doesn't work off of your legs, so forward must ALWAYS come before collection and slow loping (just ask the dressage people! lol).
As always, pull him back to the trot and ask again--remember, be polite first! (I probably sound like a broken record about that, but TRUST me, it works). When you ask, ask him like you think he's going to step into the best canter you ever sat, lol. And when he doesn't (because for the first 30 or some times, he won't lol) then you really make him go somewhere. We want to avoid the crapping 4-beating, so that's why I really want you to push him into a good canter. If he wants to go faster... fine. I'm sure that after a while (5, ten minutes) he won't think going faster was such a good idea... because he's lazy, lol. So no worries if he wants to run around like a loon-toon.
If he tries to break gait here, I only let him about ten times (Breaking at the canter to me is a huge problem, and I don't ever want a horse to think he can do it). You handle it the same way you did at the trot--let him break, then get after him because he did it. After those ten or some times, whenever the horse is not cantering the speed I want, he's going to feel some spur. After a few times of spur, the horse is thinking that maybe he should speed up when I kiss, because it's not bothering his sides, lol!
Same thing with the stop from this gait (just make sure he's solid at the other two, because it's obviously harder to do it from the canter). If he gives you a good stop, and offers the back up on his own, hell let him rest for five minutes! He'll love stopping, and he'll do it cleanly and quickly if you reward him for it.
Work on this stuff for a while. When your boy starts showing that he's moving off of your leg and really working for you, then you can start bringing his head down and getting him into the speed you want. He NEEDS to move forward for these exercises to work--that means don't let him jog or lag around! Don't drill on him too much. If he's lazy, he already doesn't want to do it, lol! If he gets something and does it right, good! Try to work on something else for a bit. Lazy horses do not do good with continuous, monotonous, repetition (nervous horses do!).
Hmm.. I think I covered everything! (ahaha, with all of that, I should have!
) If you want videos of anything, or need me to clarify anything that doesn't make a lot of sense, ask away.