Turn to God and trust the gospel
Jesus began his public preaching in Galilee by calling people to repent and believe the gospel (Mark 1:15). These belong together. Repentance is not merely wishing you had avoided a bad outcome. It is turning from a life that resists God and placing your trust in the good news of Jesus.
The Greek word often translated repentance is metanoia. It describes a change of mind and heart that affects the direction of a person's life. Peter urged his hearers to repent and turn to God, looking to him for the cleansing and renewal they could not make for themselves (Acts 3:19).
And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.
Tell God the truth
Repentance begins with honesty. Don't minimise the wrong, blame everyone else, or hide behind excuses. After his sin against Bathsheba and Uriah, David came before God asking for mercy. He acknowledged his sin and asked God to create a clean heart in him (Psalm 51:1-3, Psalm 51:10).
You can pray plainly. Name what you have done, admit that it is wrong, and ask God to forgive and change you. Scripture says that when we confess our sins, God is faithful and just to forgive and cleanse us (1 John 1:9). His mercy does not depend on how dramatic your emotions feel that day.
If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
Receive mercy, not a payment plan
Repentance does not mean paying God back until you have proved yourself worthy. None of us can undo our sin or earn forgiveness. God showed his love by sending Christ to die for sinners while they were still sinners (Romans 5:8). So turning to God also means letting go of self-reliance.
Jesus told of a tax collector who came to the temple with no defence for himself. He asked God for mercy, and Jesus said that he went home accepted by God (Luke 18:13-14). That is the posture of repentance: no pretending, no bargaining, just humble trust in God's mercy.
Paul distinguishes between sorrow that draws someone back to God and sorrow that simply grieves over painful consequences. Godly sorrow produces repentance that leads towards salvation (2 Corinthians 7:10). If you feel convicted, let that conviction bring you closer to God rather than make you run from him.
But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.
Take the next faithful step
A changed direction becomes visible over time. Paul preached repentance towards God and faith towards Jesus, then urged people to live in ways that showed their repentance was real (Acts 20:21, Acts 26:20). Good actions do not purchase forgiveness. They are the fruit of a heart God is changing.
Your next step may be very practical. You might stop a dishonest habit, return what you took, apologise where it is safe and appropriate, put distance between yourself and temptation, or ask a mature Christian for help. Start with the step in front of you.
If you fail again, don't conclude that God has abandoned you. Keep bringing your sin into the light and returning to him (1 John 1:7-9). David knew that God does not despise a humble and contrite heart (Psalm 51:17). Repentance is a first step of faith, and it is also part of the ongoing Christian life.