Will he play with other people when not in a training sequence?
For most GSD, praise is not enough. Once the problem get harder and the dog is pushed more, the praise at the end is rarely enough to motivate.
Of course without seeing your dog I can't judge his drive. Or what's motivating him, so it's hard to say. Are you doing trailing or air scent?
Sent from Petguide.com Free App
"So that others may live"