Emotion cause you being careless and most of the the it also create frustration and aggressiveness, once you already been dominated by your emotions then you won't be able to think clearly, even you begin with strategy and good anticipation everything will fall a part when emotion start to dominate, it manipulate everything.
You need to make sure that you have the courage to make that decision to stop your session if you feel that you are already being emotional it prevents you from making more mistake and lose your money.
Emotional can make us forget with everything and that can make us harm other people besides us. That will make us frustrate and aggressiveness because of our losses and will recover our losses without we can think clear what will happen to us. Emotional can bring more losses because we don't think that we already lose but want to get our bring back. Our strategy will not works good as we are in emotional condition and that can make us losing much money.
That is why we must manage our emotion and remember that is just gambling that doesn't need to be serious to play. We must limit our money and always be careful to spend the money so we don't lose too much money which can effect to our emotion. If we can treat gambling with right, nothing bad will happen to us and we can enjoy our time by playing gambling.