Basics first. You start with whatever you have with you when thrust into a survival situation. If what you start with is a fit, strong mentally prepared individual your chances of survival are better than that of someone who has multiple medical problems.
Given the best case scenario, assuming that you have no medical problems and are fit and healthy, being put into a survival situation puts several stresses on the body. Mental stress as in psychological and emotional stress as well as the physical stresses of hunger, thirst, heat, cold , bleeding, injury.
Each of these stresses will have to be dealt with on an individual basis and if not dealt with properly, may lead to serious consequences e.g. bleeding to death. Some stressors take time to show its effect e.g hunger to weight loss to malnutrition to death , others are much more apparent quickly e.g thirst to death in 3-5 days w/o water.
OK. Now assuming you have all the food and water and shelter and heat or whatever you need to keep you alive, rest will do wonders in helping you to acclimatize and adapt to the environment around you. Cortisol (the stress hormone ) levels are lowest at rest and the immune system also has a chance to recuperate. The mind is also able to function better after rest.
So, finally a summary : tend to your immediate needs e.g fire , water, shelter etc , rest when you can, so your body can adapt better to the situation as it arises.
Adding to all this about the knowledge of medicinal herbs and plants is helpful as well , as is any medication with you which may help you in the survival situation.
My S$0.01
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