As you progress, stop giving treats every time the puppy comes, but always praise. Gradually make the exercise harder by increasing the distance. If you need to keep him from becoming distracted, you can add a long cord at this stage, and give him a little tug as needed. As with all dog training, you have to add distractions, increase distances, and repeat, repeat, repeat. Avoid hauling the dog to you while calling “come,” and never call your dog to you to punish him.