I have switched to a running commute for now because I can run enough time to count for a little more exercise and I actually like it.
There's a woman I often see running in the morning wearing a pretty sizable pack so I think she does a running commute. I sometimes see her on a bike. She always seems to have a pained look on her face. I hope you are having more fun than she.
I'd rather be swimming...biking...running...and eating cheesecake...
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2008 Cervelo P2C Tri bike
2011 Trek Madone 5.5/Cobb V-Flow Max 2007 Jamis Coda/Terry Liberator
2011 Trek Mamba 29er