This is not just about controlling your emotions while gambling, the bottom line is avoiding gambling when you are emotionally unstable. Trust me, you can't help yourself and nobody too would help you if you if you consciously walk into a casino with a foul mood to gamble. At that point you are not in the right state of mind and you are most likely going to take impulsive decisions. Deciding to gamble alone is already an impulsive decision taken as a result of your state of mind at that time.

There are other things to do when emotionally down, anything that has to do with money and transacting should be avoided during that period of emotional instability because mistakes are most likely to happen.