The last ride I did, I wore a heart-rate monitor to see how many calories I burned during that 25 miles. I burned 1,000 calories on my horse that day. I am in good shape, and that is a very serious workout. To give an example, I burn 1,000 calories by running 10 miles (on my own legs and feet). So you can see that an endurance ride is not for the weak body. Preparing your body for the race should include a lot of riding. However, in addition to that, you should stay healthy. Walk, stretch and do physical activity as much as possible. The stronger you are, the better rider you are, especially when you become fatigued, and I guarantee you, that after two hours of trotting and in a saddle, you will become fatigued. Your body and muscles are tired, and you are only partially finished. Your riding will get sloppy and that will affect your horses ability to perform. Let me put it this way, if you are on you horse bouncing around at a fast trot, your horses back will become s...