This group stresses being able to stay alive for indefinite periods in life-threatening wilderness scenarios, including plane crashes, shipwrecks, and being lost in the woods. Concerns are: thirst, hunger, climate, terrain, health, stress, and fear. The rule of 3 is often emphasized as common practice for wilderness survival. The rule states that a human can survive: 3 minutes without air, 3 hours without shelter, 3 days without water, 3 weeks without food. 
DIY home surgeons will be excited to know epinephrine can actually be used with lidocaine (a numbing agent) to restrict blood vessels for faster wound repair. (Note: Cracked in no way condones performing self-surgery.) When sanitization resources become limited, the speed with which a wound can heal will have a drastic impact on survival rates. The longer a wound stays open and bloody, the more likely you are to get infections. Infections have historically been some of the most deadly and difficult-to-treat medical conditions, and even today they are not always easily survivable.
Pense invites me to imagine a world turned lawless when the ninth transformer blows. Fifteen percent of the New Orleans Police Department deserted during Hurricane Katrina—imagine if the entire force lived where the levees broke. Big box stores killed off regional food distribution centers years ago; all we’ve got is what’s inside Walmart and Sam’s Club, and if you thought Black Friday was bad, imagine the crowds when it’s life or death. Drivers fleeing Springfield will hit roadblocks, where mobs will pull people from their vehicles like the LA rioters did to Reginald Denny. You might commit vehicular manslaughter, the preppers tell me, just to get out alive.
Since people began building fallout shelters during the Cold War, canned nonperishable food has been recognized as great to have around when the going gets tough. Freeze-dried food and MRE (Meal, Ready-to-Eat) military rations with years of shelf life are also good options that take up less space per available calorie. [Doomsday Facts (and Fictions)]