Free-Will-ists (not free willie-ists) say that I observe the ability for myself to make a choice...therefore free will.
Determinists argue that the human is obviously a construct of physical components...therefore determinism (or sometimes partly random, still unchosen). Even worse...look into the timespace or arrow of time theory.
The sane position:
Compatibilism: Why are we talking as if free will and determinism are opposed? You have to very carefully define "choice" in a non-intuitive manner to make free will conflict with determinism. Let us instead use sane definitions of "choice", Free Will and Determinism. If so...there is no conflict at all.
As a neophyte philosopher, I spent years as a determinist, then more years as a free-will-er, then back to determinism for years. Finally, I discovered compatibilism...which asks the right questions.