Immunity is the body’s defense system—and more than just fighting illness, it includes nutrition, hydration, brain function, hormones, reproductive health, and the quality of one’s environment. It’s affected by daily habits, sleep, stress, and past medical history. Immunity sustains energy, focus, and physical recovery. Without it, the body can’t build or adapt. It’s the most foundational system of wellness, silently influencing everything from emotional balance to physical performance.