I have a 1 1/2 year old Border Collie, he is really intelligent and learns at a fast rate, however when I am training him he is constantly jumping for the treat or toy, biting my hands and legs. I cant put my hand anywhere near him without him going for the toy. Is this just a dog who need more frequent exercise. (I'm struggling to let him off the lead at the min) or is there something I should be doing to stop this behaviour in order to calm him down when training.