Foregoing gym visits for long hours at the office can have very real consequences. "People who sit more have higher cholesterol, blood sugar, and triglycerides," says Tom Holland, MS, CSCS, exercise physiologist and author of Beat the Gym. "They're at greater risk of developing heart disease, diabetes, and numerous other health issues." But adding small exercise breaks into your otherwise sedentary day can go a long way towards keeping you fit. Sneak any of these 20 simple moves into your nine-to-five to start.