The good thing about exercise is that the more exercise you get the more exercise you need to get tired. The bad thing about exercise is that the more exercise you get the more you need to get tired. So, as it is with humans exercise only tires out the unfit. The more you run the more you CAN run so it is a double edged sword there. Moderation and control is the key. Caesar's show is made for TV so you never see the dogs that fail in his program. You also never see him working with any real working mastiffs or Guardian breeds... well, I have not.