While Rosh Hashanah is focused on G-d’s existence, authority and supervision of the world, Yom Kippur is focused on our role in G-d’s plan for the perfection of humanity.
We’re created half-spiritual and half-physical with a strong ego, so we’re conflicted between doing what is good (spiritual) and what feels (physical) or looks good (ego).
Judaism does not deny us physical or accomplishment pleasures, rather we’re instructed to make these pleasures secondary to a focus on becoming giving, emotionally mature, G-d aware individuals.
However, because the ego and body drives are so strong, we make mistakes and instead of driving towards the long-lasting perfection of our spirit, we pursue short-lasting and often self-destructive physical and ego satisfaction pleasures.
G-d expects that we’ll make mistakes and He gives us the means to self-correct and erase the negative effects of our mistakes on the day of Yom Kippur. In fact Yom Kippur is considered a joyful day and we eat a festive meal before the day begins and one after the fast ends.
To assist us in our self-correction, G-d instructs us to refrain from physical pleasures like eating, bathing and intimate relations and we focus on the greatness of G-d and put our egos on the shelf for a day.
Eliminating our physical and self-centered pleasures gives us the opportunity to introspect, admit and express regret over our limiting self-destructive actions and negative character traits. When accompanied by sincere intent to improve, G-d assists in removing the effects of our mistakes and allocates the resources we need to become the better people we want to be.
May we be successful in using this awesome day to set ourselves on the path of actualizing the greatness each of us possesses.