Angie and I deciding long ago that we're each entitled to three one-hour workouts a week. And since my driving commute is 20 minutes and my bike commute is only 45, it feels like I'm squeezing extra time out of every day.
I'm not a super "green" guy. I have a car that I love. But there's something about that time before and after work everyday. Maybe it's because I'm an extrovert and this forces me to be alone. Maybe it's because of the adventure. I really don't know. But I don't have any intention of stopping.
If you've never tried bike commuting, you should. If you need motivation, leave your car at work and have a buddy drive you home. That way, your bike is your only option in the morning. That should get the pedals turning.