As a component of SERE, survival means staying alive and retaining the physical and mental capacity to act during military isolation. Protection from the environment, sustainment, personal equipment and self-direction preserve the person's ability to act and return to friendly control.
Military use
Under enemy threat, protection and sustainment need to be considered alongside avoiding detection. Obtaining water or food may require additional movement; movement consumes energy and increases visible activity. Concealed rest and sleep conserve strength for the next necessary movement. Survival therefore also concerns managing available resources and physical capacity.
The physical aspect includes protection from the environment, water and food, and maintaining health and mobility. The psychological aspect concerns self-direction during isolation: assessing the situation, taking stock of equipment, setting priorities and planning the next actions. Purposeful planning and thinking focus attention on tasks that need doing, including when loneliness adds to the strain.
Relationship with the other SERE tasks
During evasion, survival preserves the strength needed to continue avoiding capture. In captivity, self-care and resistance come together: maintaining personal condition and self-direction while opposing enemy exploitation. French SERE terminology calls this survival element survie en captivité, survival in captivity.
The isolated person's condition is a decision criterion for a possible personnel recovery mission. Their mobility affects the assistance needed during an actual pickup.
Terminology
Survival is the first component of the US and NATO SERE expansions. The UK's Defence SERE Training Organisation uses the verbal form Survive. French SERE capability fields call the subject Survie.