Musar על סנהדרין 43:23

The expression of פתח בתשובה, "commenced with repentance," simply means that a person does Teshuvah before he feels any ill effects from his transgression. This is to be contrasted with someone whose repentance is due to old age, when the evil urge cannot hold out the promise of gratification as a reward for the sin. I have explained Lamentations 2,3, השיב אחור ימינו, "He has withdrawn His right hand," to mean that G–d withdrew the hand held out to repentant sinners. The reason G–d did so is because we find in that same verse: מפני אויב, "on account of the enemy." The "enemy" is the painful result of one's sins. When repentance is due only to G–d's retribution, they are not compared to "crowns." Repentance and good deeds are considered "crowns" of a person, i.e. adorn him when they are caused by free willed activity, and before reverses in one's life prompt one to try "religion."