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.
I think everything is gambling is determined by your experience and probability. I do not see LUCK playing any role. Many people do not even believe in LUCK in the first place which makes it a lame concept for many. A random event could not be regarded as luck or many people do. Having said that, a winning mindset backed by experience could be instrumental in helping you win.