Between driving, watching TV, and working at desks, Americans spend half their waking hours sitting down. The problem with this is that our bodies are designed to move, and when we spend so much time sitting our health suffers in many ways.
Sitting causes the central nervous system to slow down, which can lead to fatigue. One study suggested that fatigue could be reduced by up to 65% within 6 weeks by adding low intensity exercise like walking three times a week. Sitting can also weaken the muscles that support posture and are used to walk. This can stiffen joints, and lead to hunched posture and increase the risk for back and joint pain. Sitting for a few hours can cause enzymes in your body that break down fats in your bloodstream to start switching off. Prolonged sitting can cut their activity by up to 50%.
Its no secret that the biggest traps at home are the TV and computer, so a little careful planning can add some activity to those non-active pastimes. Try placing exercise equipment like a treadmill or stationary bike near your TV and use it for at least a half hour a day. Some people choose to put their computers on an elevated shelf or stand so that they can stand while using it. Video games are just as sedentary activity as watching TV in most cases, but there are options like some of the games on the Nintendo Wii that allow you to mimic motions in sports such as tennis or baseball. While certainly not a replacement for a workout, but still much better than the alternative.
At the office, try standing up when you answer the phone, or scheduling walking meetings when there arent a lot of notes to be taken. Another good practice is the 10 minute rule, which is to get up and stretch or walk around for 10 minutes out of every hour. Try parking your car farther away from the office, and take the stairs instead of the elevator when/if you can.