Congratulations on your first commute! It only gets easier as you go along and you're going to love it!
I must be overdoing it because I just didn't have it today. Maybe over did it this weekend. I still made it, but sore-legged and slow paced. Of course, I'm going from a week of road biking to riding a fully loaded hybrid. Maybe I'll catch a 2nd wind before the ride home. Need...sleep...!