There is an eternal difference between regret and repentance. Regret feels bad about past sins. Repentance turns away from past sins. Regret looks to our own circumstances. Repentance looks to God. Most of us are content with regret. We just want to feel bad for awhile, have a good cry, enjoy the cathartic experience, bewail our sin, and talk about how sorry we are. But we don’t want to change. We don’t want to deal with God. Godly grief is a fruitful and effective emotion. The Spirit uses it to spur us into action, to make us zealous for good works, and to help us run from sin and start walking in the opposite direction. Worldly grief makes you idle and stagnant. It leads you to wallow in self-pity and pointless regret. You don’t change. You don’t grow. You don’t fight against the deeds of the flesh. Instead you just ruminate on your mistakes, obsess over the opinions of others, and ponder what might have been. Anyone can feel bad. Being changed is something else entirely. Sincere biblical repentance is as much a work of grace as not sinning in the first place.
– Kevin DeYoung, The Hole in Our Holiness, pp. 143-144.