I really don t believe in luck like something definitory. I think most of the time the emotional part plays a role in how things unfold. If you played a very likeable-to-win hand and river turns the outcome over like it happens on a numerous of occasions, it s a matter of control to not lose it and keep being reasonable when playing future hands. Or if you really overthink the situation sitting on cash games, stand up the table and try all over again. You re not becoming better at anything if you persist in errors.