Our sport doesn't offer a version of the walker's stroll, a swimmer's float or a biker's coast. Some runs are tougher than others, but none is truly easy. Running toughness isn't like the meanness that an NFL linebacker directs against a ball-carrier. Ours is a quiet, long-suffering toughness – a survival instinct rather than a killer instinct – directed as much inward as outward. Distance races aren't so much runner-against-runner competitions as contests of runner-against-self. To a distance racer, toughness means starting and finishing, enduring and improving, weathering problems and correcting mistakes. Toughness means knowing when to push and when to pull back when to psych up and when to calm down. It's dealing with defeat, learning how to be single-minded and fitting running into a full life. Your toughness is made up of equal parts persistence and experience. You don't so much outrun your opponents as outlast and outsmart them, and the toughest opponent of all is the one inside your head. [Joe Henderson]