Is free will a myth?

[Peh]

I call myself an incompatibilist. Free Will is an illusion. BUT before we go any further. You have to define what kind of Free Will you actually mean, because there is no exact definition of what abilities it has. Compatibilists for example bend the definitions of Free Will to their likings in order to fit into determinism.
But for me, Free Will is the ability to act at a certain time at a certain scenario differently than before. Meaning: You had the freedom of choosing otherwise.
While we live in a casual physical world, a deterministic world, an uncaused cause which would be Free Will in my opinion, can't happen. It would go against the laws of physics.

I bothered myself with this question for many years now and only come to this conclusion that Free Will does not exists. I've noticed that people who argue for Free Will, don't see the casual chain of thought processing and determination which are leading to the choice being made.
Later on I've found out about all the positions that exists and went deeper into it. Eventually I've found out about Sam Harris which shares my opinion on this matter.