If you’ve had a quick lunch at your desk, then get up, get out, and take a walk. Cruise around the building. Get out and get some fresh air. Or do what LinkedIn CEO Jeff Weiner does and try walking meetings: Not only will new scenery change your perspective, but you'll have fewer distractions as well. 

A 15- or 20-minute walk will let you burn a few calories, burn off some stress, and feel better when you climb back into the work saddle. Plus, you'll begin to make fitness a part of your daily lifestyle without adding to your already busy schedule.