Getting a dog to come when called is a potentially life-saving skill. But it's not easy for them. There are so many things they would rather be doing, like chasing a squirrel or sniffing a bush. Think how hard it is for us to go back to work after our vacation.
We need motivation to do things that are hard. Often that's our paycheck. A pat on the back from our boss isn't going to cut it. Sometimes a job may pay so poorly that we don't consider it worth while doing. We seek out better opportunities. It's the same for dogs. They have to be motivated to do things that are hard.
Luckily, we have within easy reach a great many delicious morsels, games of tug, and other rewards that we can offer our dogs as pay for a job well done. We can teach him that it is worth it to come to you not just in the house or when he feels like it, but at the dog park, or when he running out the front door. It is an important thing for dogs to learn .