Motivating a Lazy Horse?

My instructor is putting my on a new horse now. He is very smooth but also really lazy! I don't want to have to use spurs all the time with him, so how do I keep him going in a good pace?
He is a very good horse other than the fact that he's REALLY lazy. Any suggestions?

You have to give him a refresher on what leg means.

If you put your leg on and he doesn't do anything, get after him with a crop. Not hard, just a "hey, listen to me." Pretty soon he'll know that leg means he has to go now!

I've tried giving him a lot of leg, but he doesn't respond very well. I've been depending on my aids (crop and spurs) and I don't want to anymore.

Is he a school horse that is reguarly ridden by a multitude of riders? If so, if you only get the oppertunity to ride this horse say once a week, you're not going to be able to do a huge amount to 'train' the 'laziness' out of him. He's probably not lazy, just ignorant to the leg from being ridden by different riders of different levels, school horses just learn to ignore the leg after a while unless they get a rider on them that REALLY tells them where to go.
When you use your crop, is it on his neck or behind your leg? Neck does stuff all! You want to have a dressage whip and if he doesn't move off from a light touch of the leg, give him a good whack behind your leg to re-enforce that aid. Horses get dead to the leg because riders repeat the same aid with the same intensity constantly, or slowly build up the intensity, by this time they're usually waving the reins around and yelling and flapping their upper body telling the horse to stop while screaming at it to go haha! No wonder horses get confused??
By asking nicely once, then giving him a whack, it lets him know that you mean business. You won't hurt him, trust me! Unless your're leaving welts or cuts, its not hurting him so don't be scared! Give your reins out when you ask. If he doesn't move off from the whip, ask your instructor to stand behind with a lunge whip, and if he doesn't move off with your aids, your instructor can 'chase' him with the lunge whip. Sounds bad and I'm sure people with argue against it, but she's not hitting him with the whip, just shocking him into going. He'll soon realise that he better get that butt of his moving when you ask him to, or that scarey lady is going to chase him with a long whip!!!
Has worked for every horse I've ridden that has had going forward issues!

Ugh. I hate lazy school horses. There's not much you can do about it. Most are so tuned out to having so many uneffective riders on them. I'd personally just ask for another horse.

If you can carry a whip with him use it for encouragement. I usually use q's to encourage also. When I want a bigger walk and my leg isn't getting a repsonse I cluck. Same thing for trot. When I want canter I make a few kissy noises. I'm not sure if this will work for your horses because our are trained this way but I hope this advice helped.

School horses suck. Lol. You don't realize how much until you move off them!

However, the best way I deal with a lazy horse is to use escalation of pressure. Start with the lightest ask, then ask harder, then hardest. Ask, tell, demand.

Yes I have exact same problem with mine. Instead of perpetuating the dulling down with crops and spurs, I decided to get him tuned more into me by going from walk to trot for 5 paces then down to walk for a few paces, then immediately back up to trot then down to walk and quicker up to trot and do this a couple of times around and these lazy school horses tend to wake up more to this exercise because they are forced to pay attention and it puts a spring in their step. Now, afte 4 lessons like this, I found his motor finally. I've been riding him for several months dulled down by other students and this worked with flying colors. Yesterday I actually had to slow his trot down a bit which was so funny me and my trainer were laughing because THAT was a first. I'd rather teach him to tune-in to me and start paying attention rather than be part of the dulling process of over using crops and spurs.

Agree with the transitions comment, however not entirely with the dulling down with crops and spurs. YES if applied all the time and applied incorrectly by beginner riders or riders who have not been educated in their application they will cause dulling of the horse's sensitivity to the aids. However, if applied at the right time, right after the basic leg aid, they will sharpen the horse's reaction to he initial lighter aid.
Horse's lose sentitivity by rider's that endlessly kick them, using the system of 'ask, tell, demand'. This is a great way of training, if you know how to apply your aids properly. But usually it ends up starting with a soft kick and ending up with the rider flapping around kicking and carrying on while the horse ignores them. IMO a light aid, then a quick flick of a whip behidn the leg will get a much sharper response than continuous kicking!!

Ask, tell, DEMAND. Any horse will respond if you give 'em a good wailing. That sounds terrible, so I shall elaborate.

Ask him to move off your leg as softly as you want him to respond, usually something as light as a feather. Then get firm. Nothing? Give him a swift kick in the rib with spurred heels and a whack behind your leg with a good whip. He will go, one way or another, and he can either go when you ask nice, or he can go when you demand it.

As others have stated, don't continually kick and squeeze. If your tiny squeeze doesnt' work, use that crop until he moves forward, and then praise the living daylights out of him. Don't be gentle, you simply don't weigh enough or have enough force in your body to do real harm to a horse. Hit him hard, it will jolt him out of his lazy reverie and get his butt moving.

I HATE lazy horses. Ugh.