My old ( haha 40+ years ago) survival instructor I had kept telling us that when your in a survival situation , you will usually know it and the first thing to do is sit down , relax and don't panic. Assess your situation , surroundings, weather, your physical status , and plan from there.
The time of day it happens matters also. If nightfall is coming , maybe shelter and a fire are first order. If your not injured , count your blessings and take it from there. If the weather is hot , water may be the pressing thing. Whatever the situation , you will have on you whatever you have , so going prepared ( most of us bushcraft types do) is always important and dressing a little warmer than the weather dictates is always a rule of thumb for me. You can always peel off if too hot.
I always have a knife and means to make fire on me and adequate clothing.
