When I started running in the late 1970s, I would find a shoe, run it into the ground in six months, head back to my local Phidippides to buy another pair — and discover the manufacturer either no longer made that shoe or had drastically altered it to the point that a shoe that recently fit a short, wide foot now only accommodated a sleek Cinderella. It would take me three or four more six-month cycles to find another Mr. Right Fit — and six months later that shoe was likewise gone. I still remember the sales guy trying to console me after breaking the news that my beloved Saucony Jazz had changed and was no longer right for me.