Do no work on that day, because it is the Day of Atonement, when atonement is made for you before the Lord your God. Anyone who does not deny himself on that day must be cut off from his people.Were they supposed to deny themselves of anything else? Maybe, but that's the only thing mentioned three times along with the injunction to deny themselves.Leviticus 23.28-29
In other words, "deny yourself" doesn't always mean to abstain from sex, say, or food. And what's the opposite of self-denial? Self-indulgence -- in other words, work is sometimes an indulgence. It was back then, and it still is today. We even have a word, "workaholic," to describe those who indulge too much in this.
Why is it an indulgence? For me, when I'm doing something, I can feel productive and like I'm justifying my existence. I feel good about myself. And where is God in all that?
Which I guess is why it's good to stop. Which I will right here.