I have a Czech/DDR GSD. He has always been chronically underweight due to having no interest in food, and believe me I have tried almost everything including raw. His weight has leveled off now, however training really does not work with food. His drive is for the ball/prey, not food. This is great for something like protection where the activity is it’s own reward, but I am having problems teaching tracking and fine tuning obedience. For those activities you don’t want to use a ball as it will distract from the task at hand. How can I overcome this?