Do you have a way of keeping food cool? Not necessarily access to a fridge, but perhaps an insulated lunch sack with an ice pack that you could stash in a locker?
Boiled eggs are good for you (peeling 'em in advance makes them easier to eat). I like chicken legs and thighs which are also easily packable and eaten . You'll want to also pack some napkins and probably some salt if you go that route.
One thing I've always had a bit of a problem w/ when packing lunch or snacks is veggies. It's easy enough if you have access to a microwave, but some things aren't quite as good cold. One thing that's been working well for me lately has been making my own coleslaw. I don't have a cuisinart, but you can buy chopped up cabbage and carrots in the produce section of the grocery store. Since I don't think most commercial mayos are really all that great, I make my own - that way I can use healthier oils and control the amount of sugar, but that's probably not really necessary for you. (It isn't really necessary for me either, but making mayo is actually sort of amusing). To make coleslaw dressing, you just add 2 TBs of vinegar, 1 TBs of celery seeds and sweetener to taste to a .5 C of mayo.
Also, sometimes my grocery has brocolli chopped up for coleslaw making purposes. And, as we all know, brocolli is the holy grail of veggies.
If you can put a little more effort into prep, you can also make individual sized quiches. That'll get you protein from the eggs plus whatever meat you put in and it's a pretty easy way of getting some veggies in as well. I'm lowcarbing, so I make them crustless, which works fine and means I don't have to mess w/ a crust, but you can get premade crusts, so that isn't a big deal either way. If the thought of quiche is a bit off-putting, think of it as a savory egg pie. Eggs are traditional strong man food, you know.
For me, the most important thing has always been planning ahead. I tend to do a fair amount of cooking on the weekends and then in the morning I can just shove some things into my bag and I'm set.