Cody's book title says it all. We like this very thin microclimate of a wet 98.6 around us. We eat. Dieticians call this caloric intake; French toast,eggs,bacon and coffee, or a Mainstay bar spiced with tobasco sauce and Earl Grey Tea,in extremis Dead seagulls, ants and filtered water, Yum Yum The second method is external; a fire, radiated heat from rocks storing solar energy, chemical heat packs. The third option is kinetic energy, creating heat through exercise, aka flapping your arms while walking in circles, hopefully until you stumble upon a camp with a fire cookinig French Toast.