You could also make a big stir-fry the night before and bring some of that for lunch.

I would sometimes throw a frozen chicken breast or two on my indoor grill with some season salt(Hamilton Beach makes a grill with removeable grids for very easy cleaning and a 15 minute timer). I would cook it while showering and getting dressed.

Grab some veggies, throw the chicken in a container and you're ready to go.

Other times, I might start a veggie omelet on a very slow flame and cook that while I was getting ready.

I'm lucky enough to be able to go home and eat lunch, so I don't have to worry about take-out food temptations.