My wife, bless her heart, is always trying to get me to bring my lunch.  The reason I don't is usually because one of two things:

1) I have a lunch w/ a colleague to discuss work

2) The eBay cafeteria is so good and cheap, it really is like bringing lunch.

#2 has been shattered like a meteor hitting the Earth.  Read here:

Honey, I'm going to start bringing my lunch.