I can't take working on Saturdays seriously. It's just a five hour shift anyway, so it doesn't seem like a big deal. Also, I wear jeans.
I haven't been keeping track of how many words I'm writing a day, but my productivity has shot way up since I started my new job. I keep a spiral notebook with me almost all the time; I use it for taking notes on stuff pertaining to my job, but mostly I use it to write in when I have some down time. At lunch I pull out Bunny the Adorable Tiny Laptop and type up anything I've written in the morning, and add some more if I have time. When I get home in the evenings, I type up anything I wrote that afternoon and add some more. I figure I'm averaging at leat a thousand words a day, probably closer to two thousand, and it's totally painless.