Working in More Walking
Take every opportunity, one day a week or more often, to walk to your colleagues' offices when you need to speak with them, instead of using the phone or office e-mail.
Decide that, as long as it isn't raining, you're willing to park in the farthest parking space from the door of your building.
Keep a pair of walking shoes in your workspace, and walk during your breaks on Tuesdays and Thursdays.
Take an extended walk during your lunch hour on Wednesdays.