Each participant will be also given a pedometer, an accelerometer, and a heart rate monitor to track their daily step counts and heart rate. The walking program will consist of walking every day at an intensity of "hard" to "somewhat hard" on the Rating of Perceived Exertion (RPE) scale. Participants will be instructed to walk 15 minutes twice a day initially, then progress to 45-50 minutes a day by the end of six weeks.