If you’ve ever been a serious runner, you know more than half the battle is mental. Even the world’s best-trained athletes eventually enter into an ego battle against their own bodies.

But the issue is never can you finish. It’s will you finish? Sure, it doesn’t sound like that in your head—in your head it sounds more like “Oh dear God, please stop or your lungs are going to explode and your legs are going to melt off.” But the reality is, for periods of time, you can ignore that voice. And for periods of time an amazing thing happens—your body accepts it.