Here's an easy way to rev up your already-established walking routine: take the path of most resistance. What does that mean? Take the hard route, the one with all the hills. You might think the because you walk every day, you're in great shape, but trust me -- taking a steep hill will leave you huffing and puffing. And it will up the amount of calories you're burning, not to mention sculpting your legs.

If you're primarily an indoor walker (read: on the treadmill), this plan also works. Just keep increasing the incline on your treadmill, or if you use a fancy treadmill, use one of the pre-set workouts that constantly adjusts the intensity and incline of your walk to mimic a real outdoor stroll.