Hmmm, eerily similar to the warning label for overfed, under-exercised people, no? Dogs, like people, are not genetically wired to lie around all day. Many breeds evolved to work — retrieving, shepherding, guiding, labradoring, etc. Others are just dang hyper. So asking that they hole up all day, then loaf with you when you get home, is beyond unfair, even if you are watching "Dog Whisperer" on the National Geographic Channel.

"Fitness Unleashed" lays out a detailed four-week starter plan, both for the highly sedentary — begin with three to four walks a week of at least 15 minutes each, and those with a baseline level of fitness — five weekly walks of 30 minutes each.

The book is packed with inspiring tales of dog owners whose daily walks brought not only fitness but increased sociability ("Wow! There are other people out here walking around!") and the gratification of providing for their pawed charges.

Dog walking delivers two important staples of a successful long-term exercise program: a degree of fun and a reliable partner. People stick with dog walking because it rarely feels like work and because the animal won't bail out on an exercise date.

I can, incidentally, attest to all of the above. For 25 years, my canines have helped me discover corners of Rock Creek Park in Washington I never would have explored on my own. Plus, stooping down to pick up all that, um, output is a great hamstring stretch.

Two key cautions: Take extra care in heat and humidity. Dogs release excess heat through their foot pads and tongues only — not via all-body sweating like humans — and thus take much longer to regulate body temperature than do we. Also, if you want to try, say, cycling or inline skating, check with your vet. Some pets, by virtue of breed and fitness level, can handle sustained higher speeds; many cannot.