This is a great although brief treatment of the idea of "free will" from John Piper, Is God Sovereign Over My Free Will?. The key paragraph in his podcast comes here:
So instead of speaking of the will as free or not, I prefer to speak of people as free or not, because that is the way the Bible does. “For freedom Christ has set us free,” Paul says in Galatians 5:1. Christians are free from the bondage to sin and from the oppressive demand of having to perform our own salvation.
A lot of people get all in a twist over the idea of God messing with "mai free will!" but I have long felt that the truer description is not "free will" but "free people". The sovereign grace of God frees people from slavery to sin (Romans 6:17-18), meaning not that He overrides their "free will" but rather than He frees them from sin so that they have a true free will. Someone who is a slave to sin, dead in sin and trespass cannot have a "free will" because they are bound by sin. It is only when God supernaturally frees them from sin that they are free people who are free to follow Christ. Here is the link to the podcast, and you can read the transcript in the link above.