Richard Foster, author of The Celebration of Discipline:
There’s a back and forth—there is a role that we play in our relational life with God. That role is, as Paul puts it, that we are to offer ourselves as a living sacrifice. Now, how do you do that? I’d say primarily—not exclusively, but primarily—through the classical disciplines of the spiritual life. That’s how we offer the mind, the heart, the spirit, the body before God. Then, at that point, the disciplines have come to the end of their tether. There is no righteousness in them at all—none. They just allow us to place ourselves before God. The grace of God steps into that and begins to do work we can hardly imagine. The point of this is that I cannot change my own heart. I cannot change anybody else’s heart. That isn’t my business—that’s God’s business.