Exercise will help a canine a tremendous amount. Dogs kept in confined spaces while their owners are at work all day need more care in the exercise department than regular dogs. To keep your canine at the most healthy level there should be a set aside amount of time everyday that the dog plays a bit with someone. For the dog to keep up on his canine instincts, he will need this play time. It helps considerably with guard dogs, if that helps you make your decision.
Nothing will bring you and your dog together more than a walk every day for a minimum of ten minutes. During the walk, a tiny bit of rough play will help a ton as well. Just stop somewhere with short green grass or a sandy beach and just play a bit. The dog needs it like us humans need food and sleep. If you have a dog living in an apartment than you need to give your dog even more play. Just think of it as the smaller the space the dog lives in, the more time he needs to play each day.
If you can, find a location where you can trust your dog to roam free with no leash and just kind of get him running around. This will help keep the dog burn more calories and keep the dog from being over weight at some point in his age. A lot of dog owners find it helpful to jog with their while walking their dog. That way your getting two work outs done at once. You need to walk your dog so you might as well get your daily job out of the way while doing it.