whenever he slips out of his collar or runs too far at the park, I call his name and hold my closed fist inthe air (not threateningly, lol, just so he can see me from wherever he is), as though there's a treat waiting for him.
In the beginning, I always had a treat for him, and would call him over often, and from very short distances.
Now I have a treat waiting half the time. He's never quite sure if there's one inside my hand or not, but he likes the treats enough that he has to drop whatever he's doing and come check (just in case).
I think part of the trick is finding a treat your dog adores. Mine loves fish skins (found the ones recommeded here from sitstay.com) and the baked treats from wellness/old mother hubbard. Generally, the smellier they are, the more he likes them
