All of this is in line with the words of the Chozeh of Lublin, who said: In our generation, we’re all considered ba’alei teshuvah. The avodah of our generation is teshuvah. We have problems and we sometimes fall in, and we must do teshuvah.
One reason a person doesn’t enjoy the process of teshuvah is because he doesn’t see himself as having a clean slate afterward. And this is because the Ribbono shel Olam wants him to continue working—and so He withholds the declaration that he was completely cleansed.
Even so, we often experience that call from Shamayim after we do teshuvah. It may come in the form of a special success in learning or davening or in other areas of avodas Hashem... and the person understands from this that his teshuvah was accepted.