The immune system is the body's distributed intelligence for distinguishing self from other and neutralizing threats while minimizing damage to healthy tissue — a remarkably precise operation that most people never consciously notice until it fails or overreacts. Sleep, stress, nutrition, movement, and microbial diversity in the gut all substantially influence immune function, which means daily habits are immune medicine. Both over-suppression and over-activation (as in autoimmune conditions) represent failures of calibration, and the goal is always regulation rather than simple boosting.
Each step builds on the last.