Interesting Read for Koehler Fans It's a specific exercise that's fun to train and fun to do ; and based on Koehler's forced fetch, in the Open Obedience book. If you haven't trained that way, probably you won't get anywhere with this book. It works. You get a dog that will start on a track and stay on it, even if it's crossed by more interesting scents ; and take it as engaging work.