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True, every runner wants to quit sometimes. By any definition, becoming a successful athlete requires conquering those psychological barriers, whether you’re sucking air during your first jog or gutting it out in the final four miles of a marathon, axiomatically the toughest. When you push beyond the marathon, new obstacles arise, and the necessary mental toughness comes from raising your pain threshold. All endurance sports are about continuing when it feels as if you have nothing left, when everything aches, when you feel done—but you’re not. You have to get beyond the numbers that, like certain birthdays for some people, just seem intrinsically daunting: fifty miles, one hundred miles, one thousand miles, two thousand miles, and random points in between. At such distances, the sport becomes every bit as much mental as physical.
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