Endurance

 
Prerequisite(s): None
 
Benefit: Whenever you make a check on a physical action that extends over a period of time, you gain a +4 to that check. This applies to the following checks: Swim, Resist non-lethal damage / constitution checks to continue running, avoid non-lethal damage from a forced march, holding your breath, avoiding non-lethal damage from starvation or thirst, fortitude checks to avoid non-lethal damage from extreme weather or resist damage from suffocation.
 
 
Source: Players Handbook