Although all dogs need some exercise, not all dogs require the same amount. It's also important to remember that dog exercise comes in a variety of forms not regularly practiced by people.
Exercise needs have very little to do with size. Instead, breed tends to count the most. For example, Jack Russell Terriers and Shelties often begin to misbehave when given too few exercise opportunities. On the other hand, a mastiff and many other large dogs may be happy with a couple of daily walks in the park or a 15 minute game of catch.
Little dogs quite frequently require more exercise than larger dogs. Many of these needs can be satisfied in an apartment or back yard. If the small dog has adequate toys, or a dog or cat companion, it can generally meet all its own activity needs. However, don’t miss walking the dog on a daily basis too; a walk proves healthy exercise for both the dog and its owner.
Mid-size breeds also vary in their need for exercise. Expect dogs that are natural hunters or herders to require more activity. Beagles, hounds, border collies, Alaskan sled dogs, and Australian shepherds are naturally going to be restless if cooped up. They need time to run around, catch things, chase things, and to walk or jog.
Many of the working dogs benefit from having another dog companion. They also will benefit from visits to dog parks. A 30 minute to one hour visit to a dog park each day frequently gives the dog as much exercise as he needs because playing with other dogs requires exertion. Also expect to walk or jog with these dogs daily.
Some dogs also require mental exercise. Dogs, like people, can get bored. Certain dogs get bored enough to engage in undesirable behaviors like destroying potted plants or eating your shoes and furniture. New toys that require some work to get reward are fantastic for dogs that need a mental challenge. Also, daily interaction with your dog will help satisfy some mental needs.
Since many dogs are mixed breeds, it may be hard to know what type of exercise requirements they have. Once you get a mixed breed dog, observe its behavior. If the dog enjoys basking in the sun most of the day, it probably does not need as much exercise. Conversely, if the dog appears restless and wanders around the house or yard relentlessly, its needs may be better met by more activity. Also, older dogs tend to have fewer daily exercise needs than do younger dogs.
As with people, be wary of providing too much exercise in hot temperatures. During hot months, allow your dog to take breaks and bring along water. Also, schedule activities during the coolest parts of the day, like right before sunrise or right after sunset.