Apples, oranges, and bananas are self contained and don't need cooking. Carrots and other vegetables as well. Learn to carefully shop and you can find carrots that are actually quite sweet.
Other healthy foods that are easy to pack and hold up very well under all weather are raisins and nuts (peanuts are nuts). Most sandwiches will also fare well. You can easily find low-fat lunch meats at any grocery store.
Are you a big fan of salad? If it's primarily lettuce it's actually pretty low in nutrition. Now if you are talking red cabbage, dark green lettuce varieties, and spinach (yummie!), then yeah, you moving into the vitamins and minerals department.
I really don't think you need to avoid red meat; just eat moderate portions and look for lower fat cuts.
don't really care what people thing about what I'm eating. If my tuna sandwich stinks too much, they don't have to eat next to me.
Exactly.
Do you like salmon? Canned salmon is relatively inexpensive and is one of the most nutritious proteins that can be had from a can. (Sorry, living in Alaska I can't imagine life without salmon and halibut.)