Rabbi Schneur Zalman of Liadi's purpose in writing the Tanya was, to a large extent, to assist us in taking an accurate measure of where we stand.
Not to imagine that we have reached some lofty height or that our connection to God is strong and sound when it is not.
This awareness enables us to instruct our souls–and ultimately to repair our very beings.
The Tanya relates how Rabbi Levi Yitzchak of Berditchev was unable to lead the prayer service one Yom Kippur.
His Hasidim pleaded with him but to no avail.
"Last year," he told them, "I promised God I would do complete teshuvah. And look, the year passed by and I still haven't repented. How can I possibly lead the prayers again?"
Finally his son said to him, "Father, last year it wasn't true, but this time it will be!"
Upon hearing those words, the Rabbi took heart and began the prayers.
Cultivating the self-awareness necessary for teshuvah is an incremental process.
Part of this process is acknowledging that we may not have lived up to our goals or promises from last year–or if we have indeed made progress, that last year's teshuvah does not suffice from our new vantage point.
Who we are now is different from who we were when we repented last year.
If I did not fulfill last year's promise, that does not contradict my ability now to promise sincerely.
What is important is not what has happened–or did not happen–in the past, but whether or not a person is prepared to accept it, learn from it, and to go forward.
If we are not prepared to accept our past, including our sins and our suffering, it will come back repeatedly.
–Rabbi Adin Steinsaltz
From Learning from the Tanya by Rabbi Adin Steinsaltz