During the season of beach bods and six-pack abs, it's hard to remember that fitness isn't just about looks. It's about health -- and not just physical health.

Fitness is also about mental acuity, good behavior and an all-around feeling of happiness. This is true for humans, and it's true for dogs.

No doubt you've heard the saying: A tired dog is a good dog. Well, it's almost accurate.

If a dog that hasn't been on so much as a walk around the block since winter struck suddenly finds himself jogging across town under a blazing sun, he'll be tired, all right. But he might also be injured. Or in pain. Or dehydrated. Or feeling sick. This is not the objective, and it could backfire, as pain, injury and illness can trigger aggression.

Nor is it the goal of exercise to simply tire your dog out by setting him loose in the yard to mindlessly run around in circles. Tired is good. But tired in the right way is best.

What's the right way? Depends on the dog.

While it's true that any exercise is better than none, in most cases, owners and dogs exercising together is optimal for many reasons:

• You are there to bear witness to any injury your dog may suffer. Prompt attention and temporary restriction of activity if necessary can prevent a minor injury from becoming severe.

• Your participation allows you to tailor the type of exercise to your dog's needs. For example, herding dogs are intelligent and high energy by nature. Sports, games or even an obstacle course in the back yard will satisfy their need for physical exercise and mental stimulation. A Chihuahua, however, might be turned into a jittering bundle of nerves by such a regimen. This small breed's exercise requirements would be easily satisfied with a couple of half-hour walks a day.

• Exercising with your dog makes the entire experience as much about bonding as about getting in shape. If you carve out time every day for exercising with your dog and customize that exercise to accommodate his breed and your lifestyle, you will have created something that will both lengthen and strengthen your relationship.

Here are a few ideas of the kind of exercise I am talking about. Again, do a little research into your dog's breed to determine what kind of exercise would benefit him most:

• Most dogs will benefit from at least one long walk every day. How long should be determined by breed and current fitness level. If your dog is out of shape, gradually increase the length and pace of your walks over time.

• Supervised swimming is good exercise for most breeds. But don't just toss your dog into a lake assuming he'll be a great swimmer.

• Hiking trails provide good exercise and stimulation for dogs -- on-leash, of course.

• Set up an obstacle course in your yard for a good mental and physical workout.

• Jogging and Frisbee are tried and true forms of exercise, as well. Just remember to always have water available for you and your dog.

Bottom line: Exercise isn't about feeling tired. It's about feeling -- and being -- your best.

Woof!

Dog trainer Matthew "Uncle Matty" Margolis is co-author of 18 books about dogs, a behaviorist, a popular radio and television guest, and host of the PBS series "WOOF! It's a Dog's Life!”