It’s a gray skies snowy Sunday afternoon, the fireplace is turned on, Bull Durham is on the TV machine, and I’d rather play with POV-Ray, snooze or get back to reading Terry Pratchett‘s Going Postal than spend hours working on a blog post. Sunday should be a day of rest or, at least, of difference.
I’m not particularly stuck on Sundays; my Lutheran background programs me for Sundays, but there are other ways to keep a Sabbath.
I do think it’s important to observe one day a week that is tuned differently than your other days. I think it’s mentally and spiritually healthy to change your pace one day a week. Dedicating a day helps insure following the practice.