Fitness isn't just about exercise. A good diet, mental stimulation, socialization, and being part of family life are all just as important for keeping your dog in good physical and mental health.

The right diet

Quality food and clean water are essential to a long, healthy life. As soon as your dog arrives at your house, whether he's a puppy or an adult, feed him the best-quality food you can afford. You're likely to have a fitter dog with a shinier coat, as well as fewer vet bills.

Enough exercise

A leashed walk around the block lets your dog do his business and check his pee-mail, but it isn't enough for most dogs. Most dogs need 30 to 60 minutes a day of exercise to stay in good shape. Some pups need those minutes to be off-leash, full-out running to burn off steam; some enjoy a good long walk; and some want to go play fetch in a lake. Whatever form of exercise your dog loves the most, he'll be healthier for indulging in it.

Mental stimulation

A dog's mind needs exercise as much as his body does--the same "use it or lose it" philosophy applies to us all. Training is a mainstay of canine brain workouts. It could be as simple as learning to sit and stay and do doggie calisthenics, or as complex as training for agility or obedience competitions.

Of course, all work and no play makes Fido a dull boy, so after the serious training, toss in some playtime. Playing is another brain teaser, and dogs of all ages love it.

Interactive toys, which let your dog get pieces of food out of the canine equivalent of the Rubik's Cube, stimulate the brain. An added benefit: they're great ways to keep your dog's mind on something other than chewing, barking, and other annoying pastimes while you're at work.

Socialization

A dog who's isolated from strange people, dogs, or situations, is likely to react with fear or aggression, or a mixture of both, when confronted with anything outside his routine. A dog who's well socialized--exposed to new dogs, people, and situations--is more likely to stay confident, relaxed, and friendly, no matter what life throws at him. And that's the state you want your dog to be in when your neighbor's toddler runs up to your pup and throws her arms around his neck.

Socialization is especially important during puppyhood, when a dog's personality, likes, and dislikes are being formed. But adult dogs need it too (though if all has gone well, you can begin to focus on it less intensely once your dog is older). Otherwise, they can grow less relaxed and friendly over time. Positive interactions with the local kids, other dogs, neighbors, as well as training classes, doggie day care, and trips to the park can be good ways to meet these needs.

Of course, socialization can hard if you're dealing with a dog that's already aggressive toward dogs or people. In that case, you'll need help from a professional behaviorist or trainer.

Feeling part of the family

Dogs are pack animals, social creatures who need to interact with people as well as with other dogs. Dogs who're ignored for big chunks of the day or who spend their lives in the yard won't be happy, and their personalities will never reach their full potential.

The more your dog feels welcome in everything you do, whether you're driving cross-country, running errands, or having a family outing, the more you'll both enjoy the relationship. Being a member of the family is the absolute core of the human-dog bond.