4 mile flat commute - my "plan" is that I bought Kevlar tires (T-Serv), have pump, multi-tool, patches (never used) and waterproofs in a pannier bag, and I keep the bike well maintained.

I don't change clothes, or wear anything special except a helmet. I have a fan at my desk, so I turn that on for 5 minutes when I arrive to get rid of the excess heat now that I've stopped moving through the air. I take the final half mile very gently and the pannier bag means no sweaty back. I'm not much sweatier than if I'd taken the train and walked.

Somehow, people in every other country manage this, but in America most people think they must have the finest equipment money can buy for every endeavor (obviously all bets are off if the commute is very long or difficult).

Edit: I actually am getting to kind of envy people with a longer commute. I want to ride further - I'm just getting going at 4 miles. However, somehow just taking a round-about route to work is not an acceptable alternative. Also, my commute is not shrinking my love handles.