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.
Better to gamble when you are at peace, I mean when you are just relax while playing as your mindsets is focus to whatever plans you have and the execution is far better when you have emotions inside you.
It's good being happy in the sense of you are enjoying the game, but not because you feel that you are lucky, as mentioned, most of the time this tricks from the house triggered you to miscalculates and in the end of the day instead of getting out with some amount of earnings, you sign out empty-handed.