"The Gap and The Gain" is a guide for high achievers to find happiness, confidence, and success. The book explains that tying happiness to future success diminishes the present, and measuring oneself against ideals creates a gap. The author encourages failing as a way to improve and emphasizes the importance of being unhealthy about one's goals to achieve greatness. The book also emphasizes the need for intense commitment and healthy detachment, and the importance of hope for motivation.