אֲבָרֵ֗ךְ אֶת־יְ֭הוָה אֲשֶׁ֣ר יְעָצָ֑נִי אַף־לֵ֝יל֗וֹת יִסְּר֥וּנִי כִלְיוֹתָֽי׃
Błogosławię Boga, który mi tak doradził; nocami téż napominają mnie wnętrza moje.
Orot HaTeshuvah
More internal is the natural soulful & spiritual teshuva. This is the intrinsic ethical nature (lit. "ethics of the kidneys," Cf. Ps 16:7, TB Ber. 61a). It is the natural human spiritual tendency to walk a straight path, but when one strays and falls to sin, so long as one's soul has not been completely corrupted, then this sense of honesty causes heartache and breakdown from the pain, and one acts quickly to repent and repair the distortion so that one can feel that their sin has been erased. This part of teshuva is very complicated and is dependent on many internal and external factors. There are many pitfalls that one must be on guard from, but it remains one of the foundations on which the essence of teshuva rests.