DEUT1703 The first principle [of repentance] his regret. One must understand in his heart [I.e., not just cognitively, but emotionally as well."] the harm and bitterness forsaking Hashem entails [some foods are sweet but harmful to a person, and others taste bitter but may be good for one's physical needs. Violating Hashem's will is both harmful and bitter (Sha'arei Teshuvah Hameforash)]. He must impress upon himself that there exists punishment and reprisal, and that one's transgression will be paid for, as the pesukim say [this verse] and (Iyov 19:29), "Dread the sword, for anger against sin [brings] the sword." Subsequently, one must regret his evil deeds and say to himself, "What have I done? How could I [have acted] without the fear of God before me? How was I not afraid of the [Torah's] remonstrations against sin or the terrible punishment? For great is the suffering of the wicked [Tehillim 32:10].