I've been re-reading People of the Lie by Scott Peck. I don't agree with everything he writes, but as I neared the end of the book in the last chapter but one, I came across this absolutely true statement about free will:
Each of us is ultimately free to choose how we are going to behave. We are even free to reject what we have been taught and what is normal for our society.We may even reject the few instincts we have, as do those who rationally choose celibacy or submit themselves to death by martyrdom. Free will is the ultimate human reality.