Dogs need three key elements in their world to live a fulfilled life.
This should be obvious, but it is important for your dog to get physical exercise like walking or playing catch. And that your dog gets enough, some dogs need more exercise then others so it will depend on the dog how much. Even small dogs need exercise.
Dogs also need to have their minds challenged in order to keep them from engaging in destructive behavior. This can be as simple as asking your dog to find a certain toy or using interactive treat toys to feed your dog.
Dogs need a way to communicate with us and this comes in the form of obedience training. By teaching your dog what is expected of them they will be able to behave the way you want them.