Heat versus cold. Sweating in stillness on one side, shock and alertness on the other. I was sitting at home with a chest cold. Old school setup. Bowl of hot water. Towel over my head. Steam doing its quiet job. Airways cleared. Breathing eased. My nervous system settled. Sitting there, damp and slightly bored, my brain wandered. Steam room. Sauna. Then the opposite extreme. Ice baths. Plunge pools. Two rituals. Same promise. Better health. Sharper brain. So which one wins