If you try to imagine your will, your decision-making apparatus, as something outside of “every single fact about” the universe, as it has been perennially tempting to do, you end up in a morass of speculation about mind and matter, body and spirit, and where they intersect and how.
Just as “life” is completely embodied in the material world, and is not some extramaterial essence breathed into it; so “ego” and “will” are as well. This doesn’t make them any less wonderful or worth getting excited about
Or as I like to put it...
According to science, the human brain/body is a complex mechanism made up of organs and tissues which are themselves made of cells which are themselves made of proteins, and so on. Science does not tell you that you are a ghost in a deterministic machine, trapped inside it and unable to control its operation.: it tells you that you are, for better or worse, the machine itself. So the scientific question of free will becomes the question of how the machine behaves, whether it has the combination of unpredictability, self direction, self modification and so on, that might characterise free will… depending on how you define free will
Or as I like to put it...