1. It helps your heart.
The American Heart Association recommends 150 minutes per week of moderate exercise or 75 minutes per week of vigorous exercise (or a combination of moderate and vigorous activity) to promote heart health. Sure, a long walk each day after work can do the trick, too, but by increasing the intensity of the workout just slightly (from a walk to a jog), you can expend 2.5 times more energy.
2. He's the best motivator ever.
I dare you to try to be lazy and skip your workout when your dog's giving you those big, sad puppy eyes. Guilt trip!
3. It gives you both a (healthy) high.
Elle Woods said it best: Exercise gives you endorphins. Endorphins make you happy. Happy people just don't shoot their husbands!" OK—maybe the last part doesn't apply to you (at least we hope not), but still, the mood-boosting effects of exercise are long proven, and a 2012 study in the Journal of Experimental Biology suggests that dogs feel the "runner's high," too.
4. You'll keep your—and your dog's—weight in check.
More than 50% of American dogs are overweight or obese, and a quick spin around the cul-de-sac twice a day simply isn't helping your dog burn enough calories. Keep motivated by signing up for an event that forces you to train. Consider doing a dog-friendly 5K (WOOFipedia staff members like the Hounds and Harriers event in New Jersey) or even a race that doesn't allow dogs (you can still train together) and watch the weight drop off as you increase your mileage.
5. He'll offer protection.
Road- and trail-running is a beneficial activity for your health, but in some cases, it can be risky. Women may more vulnerable to attacks by sexual predators, but anyone could be threatened by a violent individual or a wild animal. Of course, no one wants to put their pet at risk, but merely having a dog by your side may prevent a dangerous encounter altogether.
6. He'll force you not to overdo it.
When starting a new activity, it's easy to get a little competitive. One of the most common mistakes new runners make is doing too much too soon and causing an injury. But good news! As a responsible dog owner, you're likely to be concerned about the health of your dog (if not, you're definitely on the wrong website). Here are some things to watch for that would indicate the workout is over and (oh, darn!) a rest day is in order: he's lagging behind, he's panting harder than usual, his tags are jingling differently than earlier in the run (that could mean a change in gait or breathing), or he's sluggish the next day.
7. A tired dog is a good dog.
One of the biggest reasons for behavior issues is lack of exercise (and by the way, behavior issues are one of the biggest reasons dogs are given away). Is your dog tearing up his crate mat, terrorizing the cat, or barking nonstop? Well, no wonder! He's been bred to fetch game, chase rodents, or herd, not laze around the living room for 12 hours a day. Try running with him. You'd be surprised how calm he can be once he's had an outlet to expend all that pent-up energy.
Here are some steps to get started (Men's Fitness offers more good ones here):
Be patient: Continuous exercise might damage growing bones and joints, so hold off on serious roadwork until a dog is around two.
Get the green light: A check-up to rule out any underlying health issues is a good idea, for both species.
Go slow: Too far, too fast is a formula for injury.
Toughen up: Dogs have to build up calluses on their feet, especially if they are on pavement. Booties may help with sensitive pads.
Splash down: Make sure you carry water for both you and your dog.