You should try using Spurs. Another thing is things like corn oil, and alfalfa can give them more energy. Corn oil will also give them a shinier coat. You should look up more feed things with sugar. They will give him more energy, safetly and will also mostly have at least a few benefits in other areas as well. Another thing, and I know it sounds weird, is do Liberty, or trick training before you get on. This will stretch his neck, back, and joints so they are looser and will make him a little more comfortable, and will help strengthen your bond so he will want to work harder. Hope something helps!
This is most likely not going to be a helpful suggestion. Sugar does not effectively give horse’s energy. If you want a feed to give a horse energy feed it oats or more protein. Sugar is as bad for horse’s as it is for humans. It gives empty calories that makes them fat, which means more weight and stress on their legs. This will cause them to break down faster and be less healthy. As far as teaching your horse tricks, this comes down to respect and tricks do not always help. I have seen people get a concussion because they taught their horse to fist bump with its knees and the horse kneed them in the head looking for treats.