"The truth of it is, some days feel better than others. Some days, some miles, some steps. And though a run may feel easier than it was, your legs will find a way to remind you that mileage isn’t really something you can hide from. The myth comes in the popular assumption that there is, within every willing runner, a well of energy waiting to be tapped. This promise that a switch in the brain, once turned, will make everything easy. Really, the ones who know how to dig never know if the energy will be there when they need it. They only know how to reach."