Flow is a classic and one of my all-time favorite books, and one that I re-read every few years. Csikszentmihalyi conducted famous investigations into what makes an experience truly satisfying. His book on "optimal experience" describes a state of consciousness called flow.  During flow, people typically experience focus, creativity and a deep enjoyment. Flow is more than happiness, and his insights about mental challenge and flow are integrated into our teachings at PurposeBlue.