Sitting

I've been a teacher of one sort or another for the last 20 years, but in the summer I work for a technology company. I love keeping up with all the new innovations out there, but I HATE sitting for 8 hours at a desk. During the school year, I often feel trapped in the classroom, but at least I'm up and moving - either at the SmartBoard or roaming the room to assist a student. How do people do this who have to sit all day long every day with only a 2 week reprieve each year??? No wonder Americans are getting wide in the butt.