This I agree, it's a good way to start, but not a guaranty that you can win, luck is something that it's hard to control in gambling games that are determined by luck, if it is a skill game then you have a good chance to win,a clear mind can create a good strategy but not so in games of chances.
Controlling luck is impossible. Hard or easy, you will never have that time of controlling it.
In skill based games, having a winning mindset would help but it wouldn't change the result.
It's just helping boosting up your confidence but the results will remain the same, if you are in a good positioning you will be able to performed well, every gamblers knows that by bringing good thinking inside the gambling house, you are adding a good strategy and it will increase good chance of winning and quitting with some good profits.