" Biblical repentance, then, is not merely a sense of regret that leaves us where it found us. It is a radical reversal that takes us back along the road of our sinful wanderings, creating in us a completely different mind-set. We come to our senses spiritually (Luke 15:17). Thus the prodigal son’s life was no longer characterized by the demand “give me” (v. 12) but now by the request “make me . . .” (v. 19). This lies on the surface of the New Testament’s teaching. Regret there will be, but the heart of repentance is the lifelong moral and spiritual turnaround of our lives as we submit to the Lord. "

― Sinclair B. Ferguson , The Grace of Repentance (Today's Issues (Wheaton, Ill.).)