The worst prison in the world is the prison of un-forgiveness. It locks you in the solitary confinement of your mind, bringing to memory every sin you have ever committed; replaying them over and over again, until you feel like you are the worst person in the world and there couldn't possibly be any hope of you ever being free from this mess. Suddenly, you have an epiphany and realize that you are the one holding the key that can release you from your self-imposed prison of un-forgiveness and that key is to repent of whatever wrong you have done; forgive yourself; where possible, seek the forgiveness of anyone you may have offended and then ultimately seek forgiveness from God.