Your essential handbook to staying well in the modern world The immune system is your constant guardian, fighting around the clock to protect you from disease. There's a lot you can do to strengthen this first line of defense against all kinds of threats, from COVID-19 to cancer. Now, immunologist Dr. Jenna Macciochi gives us a crash course on how the immune system actually works--and how to keep yours in shape--with authoritative guidance on:

• the best foods to eat to strengthen your immune system
• the importance of movement, and how often to exercise
• the essential link between immunity and sleep
• its surprising connection to your mental health.