Regarding the laws of Teshuva, there is one particular Halacha in the Rambam that is worth mentioning. It is obvious that one must do Teshuva for known actions like stealing or eating forbidden foods. But what also needs Teshuva are bad habits that we might have. If a person knows that he has a problem with anger or being too egotistical, or he knows that he tends to be lacking in compassion and generosity, he must also do Teshuva for these. The Rambam says that Teshuva for bad habits is more difficult to do than for forbidden actions. We must do Teshuva for everything. Rav Yisrael Salanter said that the loudest sound in the world is the sound of a bad habit breaking.