Philosophy of life looks at the person’s relationship to their world. Such a relationship is impregnated with tension arising from constant decision making. By making decisions, a person shifts their modal (possible) worlds, which include their sets of circumstances and their vistas on various aspects of life. A shift between different positions on one’s existence in this world creates structural cognitive, emotional and strategic changes that transform what is possible and what is impossible with regard to one’s life choices. The decision-making process, on fundamental life issues, is crucially related not only to one’s general values but also to one’s view of logical possibilities. The book explores the practical aspects of modal logic in decision making and casts it as the foundation of a philosophy of life.