sweating

The human body maintains core temperature within a range of less than 1°C (1.8°F) despite external temperatures swinging 60°C or more across seasons, and despite internal heat generation that — in hard exercise — rises to 20 times the resting rate. This precision requires a thermostat, an active cooling system, an emergency heating system, and dedicated fat that burns itself to generate warmth. None of it is conscious. Here is how thermoregulation actually works.