Just how much time do you spend sitting?

If you're sitting down as you read this, you are engaged in something that most of us now spend an amazing amount of time doing.

No one keeps accurate statistics on our cumulative sitting time, but the available data reveal that the average North American is seated for 12 to 14 hours each day: behind the wheel of a car (one to two hours); watching television (three hours); and parked behind a desk, working either on the job or at home (seven to nine hours). Add an hour of sitting at mealtimes and seven hours of shut-eye, and you're looking at an astonishing 19 to 22 hours of almost complete downtime.

For many, the numbers are worse. Think about the most sedentary people you know. Can you honestly say that they are on their feet for three hours a day? Probably not. Ironically, our ancestors would have been thrilled with this chair-centric lifestyle. They toiled from sunrise to sunset just to have a meal to sit down to at the end of the day. Today, we barely budge from our seats to get breakfast.

Through the genius of remote controls, dishwashers, washing machines, electric gadgets, email and Internet shopping we've engineered physical activity out of our lives almost completely. So much so in fact that some experts estimate that we burn up to 700 fewer calories each day than we did just 30 years ago. That adds up to well over 0.45 kilograms (1 pound) a week.

Consider the energy savings of a single email: if you were to walk across your office building and back to talk to someone instead of spending the same two minutes sending an email, you could save nearly five kilograms (11 pounds) over 10 years — and that's just one email a day.

Because our modern lives require so little physical effort, exercise tends to be a leisure-time activity — walking, gardening or sports — but woefully few of us find time for that, either. Surveys report that up to one-quarter of adults — and a full one-third of women — engage in absolutely no physical activity during their leisure-time.

Your goal should be to reduce your sitting time every day by one hour. That doesn't mean you have to block out a big chunk of your daily schedule or add anything to your to-do list, although you can if you like.

But whatever you do, ask yourself how much time you spend sitting everyday. If you don't like the answer, then consider exchanging sedentary activities for more movement. The trade will help you become healthier, feel better and live longer.