Nearly fifty years ago, Timothy Gallwey published "The Inner Game of Tennis," which left an indelible mark on sports psychology; subsequently, Barry Green used similar principles to author "The Inner Game of Music." As far as can be determined, there lacks a concise guide that translates key insights from sports and music psychology into practical strategies for large ensembles. To address this gap in the professional literature, we draw on the sports and music psychology literature, as well as our own professional applied experience, to discuss the benefits of psychological skills for musicians, and we present ten practical strategies to aid the development of psychological skills for large-ensemble musicians. We conclude with some final thoughts on developing the inner musician.