I should mention I have a baseline. Meaning, I have an idea what to expect, pain or fatigue, after my workouts. If it's significantly more pain and fatigue lasting longer, I pull back on my activities temporarily. My goal has always to build the baseline slowly. As you read many of us keep a log or diary of symptoms to keep tabs on triggers. Overdoing exercise is not good either, but you can't necessarily base that on pain alone. Figure out your personal baseline but keep all your muscles active one way or another, always.