Perhaps repentance means more than just telling God we are sorry for our sins. Alexander Campbell wrote:
Repentance is an effect of faith: for who that believes not that God exists can have "repentance towards God"? Repentance is sorrow for sins committed; but it is more. It is a resolution to forsake them; but it is more. It is actual 'ceasing to do evil, and learning to do well." This is the "repentance unto life," or what is truly call reformation. Such is the force of the command, "Repent, every one of you." It is not merely, Be sorry for what you have done wrong; nor it it, Resolve to do better; nor even, Try to amend your ways: but it is actual amendment of life from the views and motives which the gospel of Christ exhibits (The Christian System, The Gospel Advocate Company, p. 38).
Our faith in Jesus Christ brings us to repentance. Repentance consists of realizing that we have rebelled against God and have done unloving things to His Creation. It consists of seeking forgiveness. It requires the declaration that sin is evil and that it had no place in our lives. It means that we begin to implement changes in our lives so that sin is no longer our lifestyle. And it requires that we live our lives guided by the Spirit.
In Colossians 3 the apostle Paul teaches us to do four things we are to do in order to make repentance a reality in our lives. First he tells us that we need to set our minds on the things above; Set your minds on things that are above, not on things that are on earth (verse 2, ESV). We do this by getting God's Word into our hearts and minds. This means that we need read, study, meditate, discuss, and learn the Bible. We can't change the way we live if we continue to put the same old lies of the World into our hearts. It also means that we need to surrender to leading of the Spirit. As Paul points out in Galatians 5 the true and abundant life Jesus promised is the fruit (singular) of the Spirit. The life is characterized by love, gentleness, and self-control, but it is the result of the Spirit's transformation of our hearts.
Second, Paul says that we need to put to death the things of this world; Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry (verse 5; ESV). I think this is where we get ourselves into trouble. We justify the presence of evil in our lives, and thus it continues to have a place in our hearts. Here is an example Super Bowl commercials. The Bible talks about the evil of greed, lust, and covetousness and yet we find nothing wrong with watching 30 second ads which cost 3.5 million to air, intended to cause us to covet things that we cannot afford, and often done "sex appeal." It would seem like a radical suggestion to skip watching the Super Bowl because of this, but perhaps we cannot fully put to death things of this nature without doing something radical. When Jesus told us that if our right hand causes us to sin we should cut it off, He was teaching us that to get rid of sin in our lives requires radical surgery on our part.
Third, Paul teaches that we need to clothe ourselves in love; And above all these put on love, which binds everything together in perfect harmony (verse 14; ESV). Now the only way we can do this is to have a Spirit guided life, but there are certain intentional actions that we can do that help foster a life of love. We need to give ourselves to praying for people, to being generous with what we have, to serving those who are in need, and forgive those who have wronged us.
The last truth Paul teaches here about repentance is that we need to let Christ rule our lives; And let the peace of Christ rule in your hearts, to which indeed you were called in one body. And be thankful (verse 15; ESV). The only way the peace of Christ will rule in our hearts is when we surrender our lives to Jesus as Lord. So this means the repentance requires a declaration that we no longer want sin to have a part in our lives, we denounce it as a lifestyle, and it requires a declaration that Jesus is our Savior and Lord, that we proclaim that we are His. Unless we do this we have never really repented of our sins and our lives will remain unchanged.