Day 7: "Really?" A friend said to me today. "Taking a walk around the block a couple of times a day really adds up to a regular workout?"

Well, yes and no. At my fitness level, getting in three 10-minute spurts of moderate exercise every day is an improvement over my past exercise routines, which usually involved sitting on the couch and thinking, Wow, I really should exercise. So yes, right now, three daily walks (or other short bursts of exercise) is enough for me.

But if you're pretty fit, then you're going to need to step up those 10-minute workouts to get them to work for you. About.com has an example of a relatively intense workout that's just 10-minutes long.

That said, the science is pretty firm. If you've never exercised, even 10 minutes a day can improve your quality of life. And once you can do 10 minutes of exercise, finding time for 10 more, then 10 more, won't seem so hard.