Why 10,000 Steps?

I suppose, by now, there aren’t too many people that haven’t heard about 10,000 steps. For a wide variety of reasons, it’s a pretty valuable goal to shoot for. But why 10,000? Where did it come from? What about 9000, 8000 or 7000? Regardless of the number, moving more each day has had a significant impact on my wellness, my health efficacy and, more broadly, how I think about moving through my life.