Teshuva For Thought

Do not say that teshuva is only for aveiros that consist of actions, such as licentiousness, theft, or robbery. Rather, just as a person must repent for these, so too should search for the evil thoughts that he has and repent for anger, hatred, jealousy, frivolity, the pursuit of wealth and honor, the pursuit of food, and other things. One must repent for all these. These aveiros are more difficult than those dealing with action, for when a person is immersed in them, it is difficult for him to separate himself from them.

(Rambam)