"Luck" is based on probability and chance, which are definitely not things that you have direct control over. Yes, you can make decisions based upon a good understanding of probability and can even often do things to improve the odds in your own favour, but only up to a point. There is a very big difference between making the most of the cards you are dealt, and choosing your own (and your opponent's) cards.

I think you are referring to attitude prior to the roll of the dice and interpretation of the outcome of the roll of the dice, rather than being able to influence the roll of the dice itself - with a positive outlook you can appear or feel more "lucky", and that is generally a good thing.