No matter how badly a training session may have gone, no matter how frustrated you may feel, no matter how many times Fido has bu****ed off, try to finish every training session on a positive note.
The best way to do this is to do something simple that you know Fido can do well. Even if this is a sit or a short recall. Then praise Fido to the heavens and end the session.
This ensures that Fido ends the session feeling good about himself, about you and he will look forward to the next time. If you end training on a low, Fido will also be low and won’t be so keen to do it all again ….