You're right, there is no such thing as willpower and we're all automatons moving through the universe like planets in orbit, helpless to affect our future or how we feel about ourselves or the world.
I think you are ironically correct about that! We (including our neurons) operate at the deterministic level of physics. Measuring subconscious areas of the brain also demonstrates that "choices" we make aren't as made-by-our-consciousness as we think. Robert Sapolsky's books (especially "Behave" and "Determined" are phenomenal reads if this topic interests you.
Now that said I don't think living your life as though you have no free will is a good life strategy. The illusion of free will is incredibly important. Fortunately we humans are masters at living with cognitive dissonance and inconsistent beliefs
I know all that stuff, I was just caricaturing the person's response because I felt it was a bit glib.
I definitely do not believe we have free will in the most traditional sense, but I am a sort of compatibilist: its clear we cannot make a different choice in identical circumstances for meaningful reasons, but identical circumstances never occur anyway. A person's psychology is a sort of accumulation of all their experiences into biases for future behavior and our "will" is really just a manifestation of those experiences. But to whatever extent we can curate those experiences to produce a long term psychology that we like, I think we should do it.
