Fatigue

Fatigue is a physical penalty that will lower both your character's mobility and also, temporary, his/her mastery of any physical skills. If the fatigue penalty is -6% and his/her sword skill level is 42%, the effective skill level is 36%.

Your character will become fatigued when running, fighting and doing other strenuous tasks. A low Endurance will make your character tire faster.

Simply [.] rest or [#][s] sleep to recover from fatigue.