I don't entirely know. Partly because after awhile I get so sick of satisfying an endlessly recurring appetite that I want to remind myself that I do control it, even if only to a small extent. Partly because it's an immense test of will and determination; the desire to cave in and end the fast never goes away. Partly because there are things that I feel while on a fast that I never feel otherwise (though like I said the usual state is one of listlessness). Are these reasons enough?