I only go by bike, so regularly commute after 1 beer, 4 beers, and terribly hung over. It can suck getting on the bike hung over, but it sucks standing still hung over, so whatever. Once you get going and have some wind in your face it's fine until you are sitting again at your desk.

It might be something else. Maybe you just don't want to get up and go to work in general. Are you depressed?