I've already managed to post a couple of responses before coming here. Oops.
I recently made the decision to begin communing to work after my boss gave me his old steel, beater mountain bike. Stress from work and my general lack of physical fitness has had me struggling to keep up with the work load lately, to the point where I just run out of gas by the time 11 AM rolls round. I have tried running, which my doctor says I'm good for, but even after a year of off and on again running, the shin splints were always just short of unbearable even with the best shoes and "softest" tracks available to me. After being diagnosed with high blood pressure and just generally being sick of looking at myself in the mirror, something needed to change and that's when I made the decision to get on that crappy bike and ride to work.
I guess you could say that I am still trying to "get it together" in terms of gear and knowledge. I've already invested $200 in riding gear, and that was enough to get me on the road. Just like that, I went from nothing to a 24 mile commute. Yeah, I'm sore from time to time, but it's awesome. Apart from feeling amazing after each ride, the openness and '"uncanned" feeling that you have outside of a car is addictive unto itself. I'm already on week #2. In that time, I've scored a great deal on a gently used '10 Marin Lucas Valley ($300!), I've dropped about five pounds and I'm really looking forward to the nicer weather.
I'm sure a lot of people who wind up here ask themselves what I did on my first day out..."Why didn't I think of doing this sooner?" I wish I had.