Sooner or later, people develop a fairly stable set of ways for thinking, judging and responding; this is called one's habitual domain. Our habitual domains (HDs) grow and go wherever we go and have great impact on our behavior and decision making. When we are vital and growing our HDs are expanding and flexible; and when we find ourselves in ruts, not growing, it is because our HDs have become rigid and inflexible, as in death. This book discusses all aspects of habitual domains: their foundations, expansion, dynamics and applications to various nontrivial decision problems in our lives, including effective decision making, effective goal setting, cooperation, conflict resolution, negotiation and career management. Based on an integration of psychology, system science, management and common sense and wisdom, the book provides a simple but unified set of tools in terms of habitual domains and the behavior mechanism. The tools can be applied to expand and sharpen our capacity for knowing ourselves, our coworkers, our rivals, and our environments, and to form winning strategies for solving our problems. To make the book fun to read and the concepts introduced easy to understand and apply, the book is written in plain language with many lively and interesting examples as illustrations. The first half of the book focuses on general descriptions of the behavior mechanism and habitual domains, the second half on applications.