Musar for Berakhot 8:9

And after a man has set his mind to do penitence, he cannot achieve complete repentance if he does not take these seven things to heart : The first is that he should be aware of his deeds and know them all. There are people who think that a man cannot be called a ba'al teshuva (a penitent) — i.e., that repentance does not apply — unless he was guilty of a mortal sin like having intercourse with a married woman or with a Gentile woman, or becoming completely corrupt, or similar cardinal sin. But as far as other sins are concerned, no one knows just how to repent for them. This is not so, because anything that our Sages warned us against is more severe than the words of the Torah itself, for anyone who transgresses the words of our Sages is liable to the penalty of death (Berakoth 4b). And anyone who transgresses either the words of the Torah or the words of the Sages must repent.