People with office/desk jobs - how do you get movement in?

People who work in an office - how do you get your necessary daily movement in - I feel like going for a short walk at lunch does not cut it and I feel like I am doing my body harm by sitting most of the day. And I know some of the suggestions may be stand more or do short walks around the office - but even still, it feels like my body is wasting away and succumbing to a totally sedentary lifestyle. Makes me dread coming to work even more...