In my recent series on vacuuming, I talked about choosing shoes based on tread depth. This reminded me of a handy tip I heard once, one that made a lot of sense. If you use a treadmill in your house, buy a pair of shoes that are specifically for the treadmill and only for the treadmill. Never wear them outside. The shoes will stay cleaner, which in turn will keep the treadmill cleaner. In fact, without sending loose dirt particles along the belt as it passes by, you may even extend the life of the machine!