I just got a new job. I am working on a cattle ranch and am in charge of training one horse and exercising the mare. This mare is extremely fat. She has been out with the cows on the green grass and had a very easy winter from the looks of her. The owner pulled her out and put the horses on a dry lot after a farrier told him she will founder if he doesn't do something. So now I am in charge of getting the fat off. What is the best way to do this? I don't want to over do things with her. We have huge pastures to ride in and one of them has some very steep hills. Would trotting be better for her for awhile? I haven't ridden her hard enough to really make her sweat much the past few days, and today we just moved cattle to a new pasture, she did great. Should I be trying to really make her sweat? The other horse is perfect body weight, he looks to be tb cross and is really lean. She is a short, fat quarter horse.