1) Pick a job where you will be involved with writing software/firmware in the manufacturing business. Chances are you will be on your feet for a good part of the day, walking out to the production floor to debug various things.
2) During your daily breaks (most employers allow 2 or 3 of these throughout the day) go for a walk around where you work.
3) Take a "real" lunch where you physically leave the office instead of eating at your desk, reading slashdot. Walk to the eating place or bring your lunch and walk with it and eat it outside. That way you will get sunshine (Vitamin D) and some physical movement as well.
4) To reduce "chair time" further, actually get up and walk over to whomever you need to speak with vs. just dialing them up on the office phone system. Every little bit helps.
We are not a loved organization, but we are a respected one. -- John Fisher