Here is one of my favorite lunches:
Needed:
One Tupperware container, that can fit a salad in it
One bag of shredded cole slaw (it comes without dressing)
One can of tuna, or a bunch of cooked chicken breast (I buy it at Whole Foods from the salad bar)
One bottle of salad dressing (I use Newman's Own light honey mustard)
Cottage cheese (if you like it)
I would put enough salad in the Tupperware, and then drain the can of tuna and put it in a ziplock (or the chicken), and put some cottage cheese in another ziplock. I would then put the ziplocks in the Tupperware, seal it, and then bring that and the bottle of dressing with me to work.
When it's time to eat, I take out the ziplocks, empty the tuna/chicken into the salad, put some dressing on, seal it and shake. Then, I would put the cottage cheese on top of the salad.
It's so good, it's cheap, it's healthy, and it's filling. Plus, you don't feel like taking a nap after you eat.