Some days (during a heat wave, for example), I don't want a hot meal for lunch and I just want a sandwich and veggies so I've brought my own. You could also survive a long time on yogurt, which is available in every variety (I haven't found unsweetened yet -- even "plain" yogurt has sugar), and recognizable fruits and vegetables, if you're nervous about trying new foods, or can't bring yourself to buy a chicken at the grocery store that has the head and feet still attached.
I'll probably mention this more than once -- check out "A Bite of China," a beautifully photographed TV series about Chinese cuisine. Like the great Japanese film, Tampopo, you don't want to watch this series when you're hungry. Or at least have some Ramen on hand.