I imagine that even when your commute was fairly short, your co-workers were amazed by the fact you rode to work. Think of how in awe of you they will be when you ride to work a couple of times a week.

Think of the money you'll save by getting to work under your own power. Even if you only do it once a week, you're cutting your commute expense by 20%.

Your riding to work may inspire your co-workers to re-evaluate their dependence upon their automobile. They may start thinking of little things they can do to improve their health. (I lost 20 pounds within the first three months of taking up cycling. When people asked how I accomplished that, I'd point out the little things that make a difference, like taking the stairs, going for a brief walk after meals, blah blah blah.)

I live a mile away from work. I don't ride it because the route to work is all up hill. After getting to the top of the hill, the last thing I want to do is go to work! Even though it's only a mile, people are surprised I walk. I have several co-workers who live with a half-mile of me who drive the mile to work. Weird, enit?