It's easy. Stand with both feet together. Lift the heel of one foot off the ground while maintaining contact with the ground using only your toes. Shift your weight onto that foot and slide the other foot back while maintaining contact with the ground using the whole bottom of that foot. Repeat.

Going forward is the opposite. Stand on the ground with one flat foot and slide the other foot forward with only the toes contacting the ground.

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You don't need a weatherman to know which way the wind blows - Robert A. Zimmerman