I eat the same lunch every day: bagel w/ cream cheese, banana (or alternate fruit), and some kind of fruit juice (I reuse an old Minute Maid bottle) packaged up in the ubiquitous brown bag. I know it's boring, but I don't like carrying too much with me to work (for instance I leave my pants and jacket at work and only take underwear and a shirt with me) so a simple lunch is best.