Exercise: Walk Much?

The more moderate physical activity (like brisk walking) you do, the better. Compared to doing nothing at all, seventy five minutes of vigorous walking per week was linked to living an extra 1.8 years. Walking briskly for 450 minutes or more per week was found to provide most people with a 4.5-year longer lifespan. The longer people spent each week being moderately active, the greater their longevity.
Heart, November 2012