Emotion is just a normal part but doesnt mean that it would affect luck chance for you to win the game. There's no factor that could affect your winning probabilities.
You could be happy and think you will have a great day and later you will find out that it's not your lucky day at all, if you are happy and having a great day don't think it will contribute to your success in winning in the gambling, you don't have control and sometimes we tend to be careless when we are full of emotion, it's better to bet when you are more relaxed.
Yah, Never attach emotions for a return from an investment. When money is invested either on games, business or etc, just foresee it from a revenue perspective instead of hoping on luck or emotionally awaiting for a return. Though its really hard, it would become a winning situation as you keep practicing on controlling the emotions and depending on luck basis. Your consistency will pay you off more than the luck pays you off.