By the power of the Holy Spirit through the gospel of Christ, God grants repentance to wicked sinners (Romans 2:4). Repentance is not a one-time action. It is a lifestyle.
What does repentance look like? In The Doctrine of Repentance, Thomas Watson says there are six elements necessary for biblical repentance:
1) Sight of sin
Sin must be seen for what it is, a deadly plague of the heart. This insight must humble the person.
2) Sorrow for sin
Psalm 51:17: The sacrifices of God are a broken spirit; a broken and contrite heart, O God, you will not despise. God works to create heartfelt repentance and obedience, not just outward behavioral change. Repentance is not worldly sorrow (sorrow because you got caught), but rather it is godly sorrow (2 Corinthians 7:9-10).