Training your dog allows him to become a welome member of the family. A dog who is trained behaves well in a variety of situations. He can go on walks, he can go with you on vacations and outings, he can visit your friends.
Dog training doesn't have to be time consuming. A dog is always learning, so any time he is with you is a chance for you to train him. You can praise and reward him when he offers acceptable behaviors, you can stop him when he begins to engage in undesired behaviors, you can incorporate basic commands into the daily routine. Asking for a sit at every meal time, asking him to go to a place or to perform a down stay while you are eating dinner or watching television, a recall while you're playing in the yard with him. The dog will quickly be able to learn the behaviors that are expected of him if you use them regularly.
One of the common myths about dog training is that training the dog will "break his spirit" or make him sad. Dogs love having a routine, they thrive on knowing that there is a leader. Training should always be something fun.
Another myth is that you can't train an older dog. A dog can be trained at any age!! An older dog may take a bit longer, he might have more bad habits that will take diligence to break him of, but he will quickly begin to look forward to his training sessions.
It benefits all dogs and their owners if the dog knows a few basic commands. I find that the most useful commands to train the dog for are: "with me" (loose leash walking), "down", "stay", "come", "out" (release or give something the dog has picked up) and "leave it" (prevent the dog from getting into something).
Many common behavioral problems can also be addressed with basic obedience training, such as barking, jumping, pulling, digging, and biting, just to name a few.