Long Walks Versus Short Bursts
If 30 minutes of brisk walking burns about 75 calories and strengthens your abs, heart, and leg muscles, what does 10 minutes of walking plus 10 minutes of walking plus 10 minutes of walking do? The very same thing, of course. The only difference between getting your walking done in short bursts versus long ones is that you won't build cardiovascular and muscular endurance with short bursts of walking (or any other exercise, for that matter). But if you are really time pressed, don't worry. Just make your walks 10 minutes. The benefits aren't exactly the same, but they are good enough. And walking is better than doing nothing, even if it's just for 10 minutes.
Eventually, you'll want to work your way up to longer walks, but more than that, you'll want to find a variety of ways to make your walks more intense in terms of calorie burning and heart conditioning. Adding an incline, such as with hill climbing, stair climbing, and hiking, can help you achieve this.
Short walks contribute to overall health, but they do not constitute fitness workouts. However, short walks are a great addition to an exercise program for mood elevation and for keeping your metabolism rolling along throughout the day. For example, try taking short walks to split up your workday. Take a quick 10-minute walk in the midmorning, a 15 minute walk at lunchtime, and another 10-minute walk in the midafternoon. You'll get a burst of energy, and will probably notice an increase in your productivity.