When I worked at a call center, I'd make a sandwich every day for lunch. At the beginning of the week I'd go by the local deli and buy whatever meat and cheese was on sale or seemed good. Then I'd get some rolls or bread and good mustard. I'd also get a bag of chips and divide them into Ziploc bags, and some fruit, often bananas. To drink, I'd have a refillable insulated water bottle to fill up at work. This would all go in an insulated lunch bag, which would sit in the fridge at work until lunch time.
Thinking about that lunch made taking those calls a little easier.