The key to any successful exercise program is consistency and a gradual increase in the pace and/or resistance. Exercise has to be progressive to continually yield a return. The rule of thumb is if exercise is easy then it probably isn’t doing much to change your body. If your exercise program includes walking, walk farther, faster or up hills to keep your body challenged. When the same mile walk that was once taxing, now feels easy and can be done in less time, then it’s time to make a change to that walking routine.
Check out this interesting article… Why Walking and Aerobics Won’t Get You as Healthy as You Think