By Dr. Joseph Mercola - According to recent research, if Americans cut back on the amount of time spent sitting down, it could add years to their life expectancy. Unfortunately, most people spend a large portion of each day in a seated position. It's hard to avoid these days, as computer work predominates, and most also spend many precious hours each week commuting to and from work. Sitting Takes a Heavy Toll on Health The study estimates that reducing the average time you spend sitting down to less than three hours a day could increase your life expectancy by two years. Reducing the time you spend watching TV to less than two hours a day could increase it by 1.4 years. As reported by NBC News: "'The