A couple times a month I'll make the full commute into town (40mi round trip), but I've taken to biking every day.
Last month I biked 2mi each day...
This month I bike 3mi each day
I like to wait until biking each mile is a total breeze before adding one more, but I think it's good conditioning for someone as out of shape as I am. Those 40mi bursts once or twice per month aren't too bad of a problem since they're infrequent, but I don't want to weaken in between! And going for a nice bike ride (up hill, down hill, up hill, down hill...) with lots of scenery is the highlight of my day -- so pleasant!

Does anyone else bike every day, whether for commute or exercise or simple enjoyment?