From the tiniest toy breeds all the way up to the giants of the canine world, all dogs need exercise and play to keep them healthy and mentally sharp. A dog that simply lies around all the time becomes dull and depressed. Dogs are active animals that need and enjoy interaction with people and other dogs. Daily walks, indoor and outdoor play and training sessions all contribute to your dog's physical health and mental well-being.

The amount of exercise your dog needs depends on her age, breed, and individual activity level. In any case, your goal is to keep your dog from becoming soft and flabby. Every dog should have firm muscles and a nice waist that you can see when you look down at her.

Puppies of all breeds need lots of free play — running loose in an enclosed yard or chasing balls, for instance. This helps build strong muscles and bones. Puppies also need to practice walking nicely on leash. Protect puppies from jumping on and off furniture and running on hard surfaces, both of which can injure their growing bones and joints.

The most active adult dogs tend to be members of the sporting, working, terrier, and herding breeds. Expect to give them at least thirty minutes to an hour of good, hard exercise every day. Jogging and dog sports such as agility and flyball are great ways to give these dogs the action they need.

As your dog enters his golden years, exercise continues to be important. He doesn't need the high levels he enjoyed in his prime, but walks and play help him to remain alert and mobile. With dogs as with humans, the phrase “Use it or lose it” says it all.