I say to you that likewise there will be more joy in heaven over one sinner who repents than over ninety nine just persons who need no repentance. (Luke 15:7)

Behold, now is the season of repentance….Awake, my soul: with all thy heart be reconciled to thy God and Benefactor, and so escape His just and fearful judgment. Matins canon, Cheesefare Monday

I was entrusted with a sinless and living land, but I sowed the ground with sin and reaped with a sickle the ears of slothfulness; in thick sheaves I garnered my actions, but winnowed them not on the threshing floor of repentance. But I beg Thee, my God, the pre-eternal husbandman, with the wind of Thy loving kindness winnow the chaff of my works, and grant to my soul the corn of forgiveness; shut me in Thy heavenly storehouse and save me. Lauds, Sunday of the Prodigal Son 

He who repents rightly does not imagine that it is his own effort which cancels his former sins, but through this effort he makes his peace with God. St. Mark the Ascetic