This book is a valuable empirically proven source of information about the bi-directional effects of stress on the immune system. Its content provides a review of studies investigated the impact of stress on immunologic health and well-being. This edition explains how stress affects immunity and leads to a susceptibility for the onset of certain illnesses, including virus-related disease like common cold and COVID-19. In addition, the book explains the science behind the roles physical activities, diet, and nutrition play in helping an individual stay stress-free. It is written for those who want to understand how psychological stress influences health and how anyone can control stress to become resilient to diseases. The content can also be used as a supplemental reading material for students in the medical field.