As the title implies, this book discusses the significance of personal development as a key factor in success and happiness. The book is a collection of the most important and useful thoughts and ideas of the author, which will help you to get new insights and make your life better and happier. Since this book in intended to be as comprehensible and easy to read as possible, the thoughts and ideas have been expressed in a compressed form, leaving space for you as a reader to generate your own opinions on things. The book will give you an abundance of ideas and inspiration to go out and explore your own path on your self-development. Self-development is a lifelong journey that requires constant learning and openness to new thoughts and ideas. The goal of the book is to give you the nudge you need to figure out what you really want, what your passion is, and that you will achieve the success and happiness that awaits for you and that belongs to you. This second edition of the book has been updated with some minor changes to the chapters that existed already in the first edition. Moreover, there are now two whole new chapters in this edition to provide even more insights and ideas.