Hi @natural me – sorry for the delayed reply here!
That’s a really interesting question. As a human being, my immediate response to this question would be, probably the environment around me determines what I am thinking. However there is now a lot of evidence to suggest that the brain unconsciously decides what it wants to do long before you are aware of it. For instance, by the time your conscious mind thinks ‘I would like to raise my hand’ your brain has allready put in motion the signals necessary to do this. This has quite serious implications for the notion of free will.