When you live in a big city, it seems the world is divided into two types of people: Fast walkers and slow walkers. And while you might not think there's much difference between those who prefer to motor uptown at a good clip and those who amble idly to their destination, new studies show that they differ in one very major regard: Their lifespans.

Research presented at the IAGG World Congress of Gerontology and Geriatrics in Paris shows that, on average, those who walk fast tend to live longer. The study, which took place over 20 years and involved participants with an average age of 74, compared gait speed and longevity, and found that those who maintained a pace of 1.4 meters per second or faster were over twice as likely to be alive 10 years later -- and the gap was even bigger after 15 years. Interesting, huh? I would have predicted fast walkers to be more stressed out and therefore prone to more heart attacks, but these findings held true regardless of other factors like race, ethnicity and overall health.

Of course, walking slowly is better than not walking at all, so if you're not pounding the pavement, get moving. Already doing your share of walking? Consider picking up the pace -- and sticking to it.