Your feet are exposed to dirt and grime everyday and have a tendency to get dehydrated.  Also wearing shoes all day can prevent your feet from breathing.  This can cause very dry skin and calluses.  This is why you should use a foot scrub at least two times a week to help soften the skin and remove calluses from your feet.  By scrubbing your feet regularly, you can keep those calluses from coming back and you can keep your feet soft.  Take good care of your feet so they can take good care of you!