It doesn't effect rolls, it's just something to be recorded. You gain levels of Fatigue for failing Resistance tests against environmental conditions and similar effects. Fatigue affects Vigor, but does not inflict damage. Instead, each level of Fatigue reduces your maximum Vigor by 1, causing you to tire faster in battle. Despair affects a character’s Resolve, but does not inflict damage. Instead, each point of Despair reduces your maximum Resolve by 1, causing you to become more vulnerable to the doubts and fears that plague mortal minds. So in the example below: Maximum vigor / resolve would be 10, 3 points of damage have been taken and 2 points of fatigue / despair are being suffered.