Using whatever skills, tools and the will available to you to not die. It might be being able to start a fire while you are soaking wet and it is 10 degrees out. Being able to talk your way out of a bad situation. Being able to fight your way out if needed. Being able to run faster than the other guy if you are being chased by a bear. Growing a garden to provide food when there is none to be had.
My great great aunt was in a Nazi work camp with her kids in WW2. She did whatever she needed to do to get the guards to let her out into the forest to gather wild foodstuffs. That food helped keep her and her 2 children alive. She had the knowledge to know what plants were good and the courage to do what needed to be done. Thats survival.