Your dog needs exercise, discipline, and love. In exactly that order! If your dog could ask you for what he wants, this is what he would tell you. Unfortunately the majority of dog owners believe that loving and cuddling a dog is going to make him happy and that affection is all he needs.
They do not consider that a dog needs mental and physical exercise too. If the energy has no way to go but to build up and up and up, the dog is going to develop some kind of unwanted behavior; in most cases aggression, digging, chewing on furniture, barking excessively.
Exercise is the most important part of your dog's life. You have to walk him every day, or even better, twice a day for at least 30 minutes for each walk. A walk means more to your dog than just eliminating himself, but instead it fulfills his instincts to walk for food. A backyard is not enough; it is just a big cage for your dog! Structured daily walks are so crucial to your dog to feel like a dog.