Getting rid of the sheretz is a life long task. The reason we are in this world is to make it a fitting place for HaShem. It is our job to purify ourselves and our environment, but this must be done with בשמחה ובטוב לבב. The time and place for reflection and teshuva for everything we do wrong is krias shema al amita. This includes time wasted when we had the opportunity to learn Toarah.
Here is a few lines from the first chapter of Tanya
וצריך להבין, דהא תנן אבות פרק ב׳ : ואל תהי רשע בפני עצמך
This requires to be understood, for we have learned in the Mishnah [Avot, ch. 2],2 “Be not wicked in your own estimation.”
How, then, can we say that an oath is administered to the soul that it regard itself as wicked, when this directly contradicts the Mishnaic injunction not to regard oneself as wicked?3
וגם אם יהיה בעיניו כרשע ירע לבבו ויהיה עצב
Furthermore, if a person considers himself wicked, he will be grieved at heart and depressed,
ולא יוכל לעבוד ה׳ בשמחה ובטוב לבב
and consequently will not be able to serve G‑d joyfully and with a contented heart;
Apart from the previously mentioned contradiction from the Mishnah, an additional question is now raised. A cardinal principle in the service of G‑d is that it be performed with joy — joy at the privilege of serving Him either through performing a positive command or by refraining from that which is prohibited. How then can one be required to take an oath to consider himself wicked, when this will cause him to be depressed, making it impossible for him to serve G‑d with joy?
Furthermore, just as the first part of the oath, “Be righteous and be not wicked,” is vital to his success in realizing his life’s mission, so too the fulfillment of the second part of the oath, that he consider himself wicked, is imperative. How can this possibly be so, when such an attitude hinders his joyful service of G‑d?