This past summer someone finally convinced me that guilt is your way of punishing yourself for doing what you wanted to do anyway, but didn't think you deserved. (I'd basically read a large book in a single day, and while the boys were fed and safe and reasonably well behaved, I felt that I would regret not having interacted with them some day in the future when I had time to read but no boys to play with. But still, reading that book at that time made me very happy, and she didn't like seeing this useless guilt thing kill my happiness.)