To begin, let us say that repentance is a change of mind. It is something you can do while you sit listening to a sermon or while you are reading the Bible or just meditating. Speaking of two sons, Jesus said that one of them told his father that he would not go and work in the vineyard, but "afterward he repented and went" (Matthew 21:29). What is meant here? Simply that he changed his mind and went to work. Repentance is a change of mind.
But repentance which is involved in being saved is not just a change of mind. It is a change of mind toward God and toward sin. Paul teaches that godly sorrow produces repentance (II Corinthians 7:10). Not jut any sorrow will lead to repentance; it must be godly sorrow. One must realize that he has offended the Majesty of heaven and must be sorrowful toward God. This kind of sorrow will lead to repentance.
And, then something must follow repentance. John the Baptist told his hearers to "bring forth fruit worthy of repentance" (Matthew 3:8). After a person has had a change of mind toward God and toward sin when he truly repents, then a change in life is to be expected. He will leave off sinful practices that have hitherto characterized his life and he will begin to do godly deeds that he has not been practicing.
Repentance is a change of mind that is produced by godly sorrow and which leads to a change of living. Repentance has both a cause and an effect. It is the change of mind which stands between that cause and effect.