my free will is that my brain decides for what i think should be the best for me/others/whatever. so, just because my brain is doing that for me doesn't mean i have no free will. my brain is my brain, whatever the reason is that i do it because of my brain i do it because it is the will of my brain -> my free will
that's how i define free will, not if i can do something which isn't my preference just to proof myself that i can decide against myself and my brain.