Have enough water, food, and provisions to stay warm. Be prepared to fight if necessary. Look at the riots in Detroit - over unions!! - and understand that people will fight for any reason. Hunger is an even greater motivator.
Look into supplements for military personnel. You'll want to have the best quality equipment, nutrition, and readiness in case something were to happen. And even if the world doesn't end on 12/21 - you never know when a crisis may erupt.