How does one confess? He says, "I have sinned to you, my Creator, I have transgressed and committed iniquity before you by doing such-and-such. I regret, and I am ashamed of what I have done. I am committed5 never to repeat this act." These are the fundamentals of Viduy (Confession of Sins). The more one confesses and elaborates6, the better.
How does he repent on Yom Kippur when it is forbidden to write? This same question may be asked about one who is paralyzed and cannot talk or write. The answer is, that penitence is not bound to the mitzvah of repenting. As long as God understands that in his mind and heart he regrets the sin and will not repeat it again if given the opportunity to sin, he has repented even if he was unable to perform the mitzvah of penitence. Nevertheless, if he had the opportunity to repent before he became paralyzed, he must also repent the sin of not fulfilling the commandment to repent, because he may die without having the ability to fulfill this mitzvah.
5 In chapter II, law 8, in this work, the author states that in our prayer books there is a simple form of confession, we have sinned by doing so and so. As stated before, this amount of verbal confession is enough providing that in his mind and heart he regrets his sin and resolves never to repeat it.
6 Question, if one repents his sin and is forgiven, why is it important to elaborate and continue confessing? The answer is, that when one sins, repents, and is forgiven, he has not yet completely purified his body and soul which were spiritually contaminated through his sin. These defects are remedied through greater levels of penitence. Furthermore, even after being cleansed from the sin, it is still meritorious to confess the past sin so that he be constantly reminded never to repeat this action, because the one who has tasted sin is more prone to repeat it.
Rabbi Yona in his book of repentance titled "Shaarai T'shuvah," lists twenty levels of repentance. They are;
1. One must regret his sin because he violated a commandment of God, not because of social reasons.
2. One must commit himself under any circumstances, never again to violate this commandment of God.
3. One should grieve that he did not obey the commandment of his Creator.
4. One should feel pain that he did not obey the commandment of his Creator.
5. One should be concerned about the punishment that will be meted out to him because he did not obey the commandment of his Creator.
6. One should be embarrassed because he did not obey the commandment of his Creator.
7. One should humble himself by adopting a humble personality until he completes his penitence. After penitence, he should adopt a mediocre personality.
8. One should humble himself by living simply during his penitence. Afterwards he should adopt a middle class life style.
9. One should attend to his physical needs with the objective of fulfilling mitzvos. Taking care of his health is a mitzvah, and further allows him to do more mitvos.
10. The part of the body that did the sin should be trained to do more mitzvos. If his hand stole money, then the hand should be trained to give charity. If his lips spoke slander, then his lips should be trained to teach Torah.
11. One should search his body, soul, and lifestyle in order to implement improvements and needed changes for him to become a God-fearing person.
12. One should realize the seriousness of the sin through studying the type of punishment that is meted out for such a sin.
13. One should realize that punishment for a sin is related to the degree that one does the misdeed. There are sins that may seem light sins because, if one repents, one is forgiven without punishment. Yet, if he does not repent, and if he sinned in order to anger God, his punishment may be more severe than one who violated a command whose punishment is death but if he repents, he is forgiven after suffering. Therefore, he should regard a light sin as a severe sin.
14. One must verbally confess one's sin.
15. One must pray to God to forgive one's sin.