Alan
Listen carefully: you have the biological equipment to be able to be self aware and think abstractly,
I do this often.
I think about the source of my self awareness.
I think about what controls my thoughts.
I think about my ability to generate and perceive conscious thought
I think about the limitations of what can be achieved by physically predetermined material reactions
However you don't think in isolation from others, from events, from experiences, from influences or from your personal traits and capabilities - you might have noticed that we are all different.
I have noticed how remarkably different we are from other animals
When you talk about being 'free' to choose which words to type when you post isn't somehow separate from determinism - after all, you are dependent on your language skills regarding how you express in prose whatever it is you are thinking, and what you are thinking involves the various aspects I noted above - and these are constraints, else we could all write poetry as well as, say, Heaney. So your choice of prose is understandable and unremarkable, and in your case quite predictable too.
Yes, I am free to choose every word I type.
But I think about what determines my choice.
And I have to conclude that my choice is determined by me of course.
But I think about what comprises me.
And I think about how I can possibly be determined by nothing but predetermined physical reactions of material elements.
And I continue to think about many things, because I have the
freedom to think, to perceive, to interact, to control, to manipulate, to change, to pray, to bear witness, to discover, to create, to love .......