Instructors at SERE (Survival Evasion Resistance and Escape) school recommended catching a lizard or a toad, tethering it to your shoulder, and making it a pet. Not entirely intended to be a joke. Gives you a project to focus on aside from just pure survival (e.g. catching the critter). Also gives you a pal (like Wilson). When someone asked how to feed the thing, the instructors just shrugged and said "don't bother, just catch a new one when the old one croaks...).