Editor’s Note: This book excerpt has been lightly edited and condensed. I believe that our lives will shrink or expand in direct proportion to the level of courage we possess. Staying in a space we ...

Robert Rosenkranz is a self-made billionaire. His key to success: stoic philosophy. In his new book, “The Stoic Capitalist: Advice for the Exceptionally Ambitious,” Rosenkranz shares how ancient ...