I can understand the idea of determinism but have hard time believing that my choices are being made for me. Like I had no choice to post this.?.
That's not what determinism means (at least not Causal Determinism, which is what most people think of when using the term).
It is still YOU making the choices, except that they are predetermined by your genes, the sum of your experiences and the sum of conscious and unconscious signals at your disposal at the time of making the decision.
This means that decision-making is a much more unconscious process than we usually have been led to believe and it also means that it is in THEORY possible to accurately predict each and every decision you every make in each and every situation.
In PRACTICE this is impossible, if for no other reason, then because of the sheer amount of data that would have to be taken into account.
But it is important to note that determinism does not suggest some kind of puppet-master pulling your strings. It is still you making the decisions albeit in a manner that is predetermined by the conditions mentioned above.