From the NYTimes:

Wrong: Sitting at your cubicle. Better: Walking while clicking and talking.

Your chair is your enemy.

It doesn’t matter if you go running every morning, or you’re a regular at the gym. If you spend most of the rest of the day sitting — in your car, your office chair, on your sofa at home — you are putting yourself at increased risk of obesity, diabetes, heart disease, a variety of cancers and an early death.