The best thing you can teach your horse is that legs don’t just mean “Go”. You shouldn’t have to kick for every stride. He should continue at the same speed until you tell him otherwise. It’s easy to get into a habit of kicking every stride but eventually your horse becomes dead to it.
Become a lazy rider. Teach your horse to go forward from the slightest of squeezes. You’ll need to be consistent and patient but it will be worth it in the end.
Warm up as usual but be prepared to spend the rest of the session in walk. Once he’s picked it up you’ll find the other paces come a lot easier but trot before the penny’s dropped and you’ll be wasting your time and energy.
Start by riding large and expecting him to walk from one marker to the next without you having to kick. At each marker give him a squeeze but if he slows down before because you’re not kicking then you need to use your whip.
When you use a whip don’t dither. Use it and mean it. It’s better to use it once and get a reaction than have to use it five or six times and get half the response. Riders often feel guilty about using a whip but never worry about banging at their horses sides with their heels. Which would you prefer?
You may find initially that you have to tap him every few strides but if you’re consistent he’ll soon learn and you’ll find you’re able to get further and further without using your leg.
Your aim is to increase the distance you can go without having to kick on. All horses can learn to do this in all three paces. Their riders just have to believe it too.