Being in a good mood won't necessarily make you a winner, but being in a bad mood will almost assuredly make you a loser. Starting since time began, the number of people who have won large sums of money through trading while feeling depressed, irritable, or angry could probably be counted on the fingers of one hand!
In short, try to trade when you are in a good mood. Restrict yourself to times when you feel confident, alert, comfortable, and positive.
Also, if there's something you don't feel quite right about — you didn't sleep well the night before, or you are a little out of sorts, or exhausted, or whatever it is — don't trade. These things have a way of coming back to haunt you in trading situations.