I am not a racer. Last year and this year, my work sponsored a bunch of guys to participate in a local duathlon/triathlon that benefits the military. I did the duathlon (run/bike/run), and mostly my training focused on running (which I absolute loathe), but occasionally I would run before and/or after commuting to practice transition and putting them back to back. And sometimes I would incorporate some intervals into my commute.

But mostly I'm just too lazy. My commutes are usually like something between a casual and brisk walk. About the only time/way I make an effort to go faster is to get in the drops when I'm coasting downhill.