A new study by researchers at the U.S. National Cancer Institute found that staying physically active after age 40 seems to increase your lifespan between two and seven years. And the more you exercise, the longer your life expectancy -- regardless of your weight. The study shows that just walking for a couple of hours can add years to your life. Paul Linnman talked to Dr.Eric Hansen, oncologist from The Oregon Clinic. Dr. Hansen is such a believer that he owns a “TreadDesk” so he can walk and work at the same time. In fact, he walks though this entire interview, much to Paul's surprise.