Sitting at your desk all day works your brain, but it certainly doesn’t work your heart. Cardiovascular disease is the No. 1 killer in this country, and a lack of physical activity is partly to blame. That’s why for April 7, National Start! Walking Day, the American Heart Association is calling on bosses to let their employees wear sneakers to work and take at least 30 minutes for an active stroll. Find out how to get your company involved at startwalkingnow.org.