The Zera Yitzchak (a sefer written by a chavruta/friend of a Rebbe of mine from Yeshivat Torat Shraga in Jerusalem,) makes notes of the fact how Yom Kippur is different than other fast days. On other fast days, we fast due to calamities (e.g. Tishabav) or times of plight for the Jewish people (e.g. the Rabbis even nowadays in modern Israel and at a more serious level during the times of the Mishna decreed fast’s during times of rain. However, while on Yom Kippur the Torah commands us to afflict ourselves (Vayikra 16:29), unlike the other fast days Yom Kippur is considered as “ A Shabbat Shabbaton (a Shabbat of supreme rest (Chabad.org trans. of ibid 31)) and is considered a day of joy.
One of the main reasons why this day is considered a day of great joy is because it is on this day that GOD gives us a chance to atone for the wrongdoings we have committed in the past year. On this day we pour out our hearts to GOD praying all day that he should atone for our sins as well as ask for forgiveness from other people leading us to complete atonement at the conclusion of the day.
Another major theme on this day demonstrating the great joy one should feel on this day is the intense love GOD demonstrates for the Jewish people on this day which is seen throughout our mesorah (tradition) in the Talmud and in our prayers.
In fact, it is no coincidence that Yom Kippur is a day of intense joy because of the second chance GOD gives us due to the intense love HE has for the Jewish people.
May we have confidence that this year we will be sealed in the book of good life and remember just how much GOD loves us.
Gmar Chatima Tova ( may we all be inscribed in the book of good life and be blessed with an abundance in spiritual and material matters)!