Harsh conditions or long exertions do not easily tire you.

<php>echo “<b>Benefit:</b>”;</php> You gain a +4 bonus on the following checks and saves: Swim checks made to resist nonlethal damage from exhaustion; Constitution checks made to continue running; Constitution checks made to avoid nonlethal damage from a forced march; Constitution checks made to hold your breath; Constitution checks made to avoid nonlethal damage from starvation or thirst; Fortitude saves made to avoid nonlethal damage from hot or cold environments; and Fortitude saves made to resist damage from suffocation. You may sleep in light or medium armor without becoming fatigued.
<php>echo “<b>Normal:</b>”;</php> A character without this feat who sleeps in medium or heavier armor is fatigued the next day.