It was after the tracking experience that I started using food treats to reward the dogs for correct behavior in the obedience classes. Tiny morsels would be held in front of the dog's nose and then slowly raised and brought back so the dog raised his head and then sat in order to see the morsel better. "Good Sit!" And the dog was rewarded with the food.
Food was also used to attract the dog's attention while it was being guided across the agility dog walk boards or through tunnels. Did you know that dogs have a one track mind?
If they are concentrating on the food, they can't think about the hollow sound their toenails make on the board raised only one inch off the floor. Puppies aren't afraid of this hollow sound but most adult dogs stop cold at the first click.
Then there are the dogs that are not food oriented. With these animals, the trainer needs to watch the dog to see what captivates him. I had a dog like that; food was often ignored, but a squeaky toy? Ahh, the squeaky toy always was accepted, and I used this love for both rewarding and training purposes. Some people toss small chunks of beef jerky in front of a dog on a "down-stay" to proof him, I would walk off and toss plush squeaky toys on either side of my dog. At a release command, she could select her favorite to squeak. I taught her to pay attention by squeaking a toy when she looked away.
The next trick devised to reward the dog without food incentives was the "clicker." The theory behind the clicker (also called a cricket) is that the moment the dog responds correctly the trainer gives a click signal and verbal praise. In the beginning, food must also be offered, until the dog understands. Then the food is offered less and less frequently until the click and praise is all that is needed.
Know your dog and make training fun.