I don't actually think it takes that much extra time to bring a lunch to work. As The New York Times' Mark Bittman explains, bringing a bagged lunch to work instead of eating out all the time isn't as difficult as many people think. And it doesn't have to be uncool.
Check out his blog on cheap & easy ideas for bringing your lunch to work. He also offers a few staple recipes. And the next time you're getting ready in the morning for work, try bringing some leftovers or a snack instead of eating out.