Athletes and the people who coach them may be unfamiliar with stoicism, but they are stoics. They endure pain or hardship without feeling or complaint. They control what they can control. They talk ad nauseam about controlling only what they can control. They’re on to Cincinnati. They stay in the moment, and take things one game at a time. And by doing that, they are voicing a philosophy—living a philosophy, training under a philosophy—without knowing of or understanding it. ... “Stoicism as a philosophy is really about the mental game,” Holiday said. “It’s not a set of ethics or principles. It’s a collection of spiritual exercises designed to help people through the difficulty of life. To focus on managing emotion; specifically, non-helpful emotion.” ... this was the exact kind of stuff they were exploring—not how to hit better, or pitch better, but how to sleep better and travel better and recover better and think better. That made the connection between the book and the sports world clearer. ... “Stoicism is the distinction between what you can control and what you can’t,” Holiday said.