This paper analyzes the concept of optimal experience, also known as flow, developed by Mihaly Csikszentmihalyi. Based on positive psychology, the theory of optimal experience explores the state of complete immersion in an activity and presents a new paradigm within the framework of human happiness. The paper begins with a historical overview of Csikszentmihalyi's contribution to the theory of optimal experience and the broader field of psychology of positive experience. After that, a conceptual analysis will be used to define the concept, as well as the issue of translating the word flow into Croatian language. Philosophical principles of optimal experience are explored through the prism of elaboration of the main philosophical terms in the theory: consciousness, psychic energy, play and autotelic experience. Consciousness is analyzed through Csikszentmihalyi's phenomenological model based on information theory, and the views of John Searle and Edmund Husserl are also considered. Furthermore, the paper explores how optimal experience can serve as a possible solution to the mind-body problem in philosophy. Finally, the discussion of happiness places optimal experience in a broader philosophical context, exploring how the philosophy of happiness within the framework of Plato's and Aristotle's philosophies can be reinterpreted through the prism of optimal experience. The paper concludes that the optimal experience can represent one of the key elements of a happy life, connecting the theories of psychology and philosophy in a meaningful understanding of human happiness.