It really isn't that hard to take a packed lunch/dinner to school/collage/work/university/the theatre. Most places are obliged (at least in Australia - I don't know if it is the same in the US) to provide basic "Food warming & storing" appliances (ie a microwave and a fridge).
Plan out what you are going to eat in advance, then pre-prepare as much of it as you can. I eat stirfry at least once a week. So I make sure I have pre-cut all my vegetables and my meat, so all I need to do is combine them in a wok and mix up a sauce (which I usually do in the wok whilst everything else is cooking). I make sure that I cook enough stirfry that I can also take it for lunch the next day.
Combine that with rice (A rice cooker is the best investment I made as a student. Put the rice in, wash out the starch, top up with water to the line, add some salt, put on and walk away. When it is done cooking, it stays warm, fluffy and perfect for up to about 2 hours (after that it dries out a little too much) so you can do homework whilst it cooks, and don't have to watch the clock) and you have a perfectly healthy meal or two.
I was given a book called "100 quick meals with less than 6 ingredients" - or something close to that, I have too many recipie books - which has decent meals that don't take much time to cook or prepare.
And don't rule out the common sarnie (aka sandwich). It does not have to be boring. Chicken, avocado and cheese is beautiful. You can also add sundried tomatoe for more kick. Slap it under the grill for a few seconds... bliss. Try to use different breads like sourdough, foccacia, bagels etc. Even a simple salad sarnie can be turned an oral masterpiece - another personal favorite here - thinly sliced sourdough, lettuce (iceberg lettuce, ripped off leaves, not sliced into thin strips...), tomatoe (if taking to work, take the tomatoe in a separate container and add just before eating), carrot (shredded), beetroot (same as tomatoe if taking to work, as you want the beetroot to be nice and moise) and cheese (I lean towards Old English/Tastey over cheddar, but whatever floats your boat).
And to add a bit of pep to your life. Curry. Probably not the healthiest food arround, but it clears out the digestive tract, tastes good, and has a bit of kick.
My personal opinion is frozen food sucks. Instead, call in at a deli or some other fresh food place and grab something there instead. I would much rather pay AU$10 in a cafe for a meal than about the same at McDonalds for a meal, or for a frozen meal. There is only a few dollars between them really in price, and at least the cafe's food is somewhat fresh and somewhat healthy.