We must correctly distinguish regret, remorse, and true repentance. Regret is an activity of the mind, whenever we remember what we’ve done and ask ourselves, “Why did I do that?” Remorse includes both the heart and the mind, and we feel disgust and pain, but we don’t change our ways. But true repentance includes the mind, the heart, and the will. We change our mind about our sins and agree with what God says about them; we abhor what we have done; and we deliberately turn from our sin and turn to the Lord for his mercy.

Warren Wiersbe

The Transformation Study Bible (NLT), Colorado USA: David C. Cook Publishers (2009), supplementary commentary by Dr Warren W. Wiersbe, p.1398