Cycling to work is a great idea for a number of reasons. If you live within 10 miles of your job then consider cycling instead of taking the train or getting stuck in traffic.

Commuter cycling

1. Saving money - with train fares rising above the rate of inflation and petrol costs spiralling out of control, many workers are forced to cycle for financial reasons. You'll save a lot of money once you've spent the initial outlay on your bicycle.
2. Helping the environment - leaving the car at home means less pollution and better atmospheres in our cities. As populations grow, traffic density and thus pollution in cities is growing at a rate of knots. Do your bit for the planet and cycle in. 
3. Keep fit - cycling is a great form of exercise, helping you improve your cardiovascular fitness as well as not putting too much strain on your joints - more than can be said for long distance running.
4. Lose the stress - exercise releases endorphins - the feel-good chemical in the body. Being outside will also help you relax more. Then add on the fact that you won't have road-rage, traffic jams, parking problems or strange people talking to you on the bus and it's a no-brainer!
5. Speed - in some cases cycling in to work will be quicker than driving or waiting for a delayed train. Try living in a city like London or New York and you'll see how viable an option cycling in the rush hour is. The only problem is you've got no excuse to be late!

There are of course downsides such as the weather, risk of injury and pollution. If you're worried about any of these then why not cycle on sunny days only? Give it a try!