You shall afflict your souls [i.e., fast] on the ninth day of the month at evening

A question is asked in the Talmud (Yoma 81b): "Why does the Torah state 'on the ninth day,' when we actually fast on the tenth of the month, on Yom Kippur? To teach that a person who eats and drinks on the ninth [in preparation for the fast] is considered to have fasted on both the ninth and the tenth." And why is eating on the day before Yom Kippur deemed so important? For, eating for the sake of heaven is far more difficult than fasting for the sake of heaven. (Malbim)

G-d's infinite capacity for forgiveness

The dynamics of forgiveness between human beings are different from the dynamics of forgiveness between man and G-d. When a human being wrongs another person and apologizes, the wronged party will find it difficult to forgive him if he goes and does the exact same thing again; a third or fourth time. But this is not the case with G-d. Because His forgiveness is derived from the Divine attribute of mercy, which is endless and infinite, there is no difference between a first and thousandth offense, provided our repentance is sincere. (Tanya)