Move around a bit while watching TV. The average American watches about five hours of television a day, and that amount increases as people age. At least once an hour, stand up and walk in place, swing your arms, or do some easy stretches. Whenever you drive somewhere, park somewhere farther from the door to climb a few extra steps.
If you're shipping a cement mixer truck, take the time to get out and stretch your legs before continuing on your journey. Use the stairs instead of the escalators or the elevator, even if you only climb one or two flights of the total.