No one doubts that our life is complex, and even more so in these times of pandemic and economic crisis. Today, daily difficulties are increasing, causing more stress, anxiety and anguish. But serene people face problems more successfully: They know how to set priorities, stay calm, be gentle, and instill confidence, security, and good humor. Serenity is necessary to flourish in life and overcome obstacles. To achieve this, it is necessary to have good mental health, which does not depend so much on our intelligence or amount of knowledge, as on our desire to learn and assimilate new things. Having a "passionate curiosity", as Einstein affirmed, will be very positive for our brain and will allow us to use it well and thus lead a more serene life. Throughout the ten chapters of this book, the author, resorting to Neurobiology, Psychology and Anthropology, will describe, with precision and clarity, a series of questions and give some advice that will provide us with the necessary clues to live serenely and achieve, as Aristotle would say, an eudaimonic or successful life, in which we can face daily problems with guarantees, and achieve happiness.