I do bring my clothes in to work in advance... I pick a couple of my favorite outfits, and leave them at work. Then I have extra incentive - on those days I don't want to ride, I know I have to if I want to wear that great shirt!

I wear a small Camelback and put my lunch in there (no water pouch) - yes, it's a little sweaty, but I don't like stuff around my waist. Besides - the Camelback is insulated, so my sandwich has a better chance of making it without overheating!