Stay calm: This is the key. Daily work is accompanied by adversities, setbacks and problems. Most of them are hardly major and can be solved with a calm head. The moment you get agitated, it will lead to a new set of problems which might include lack of motivation in your juniors. That can be dangerous and also lead to attrition for which you will be held accountable. Even if that is not the case, why not be at peace with yourself anyway?