I work full time and go to school full time, my husband works nights (and I need to drive him to work so I have our one car for kid transporation), and my boys participate in karate and cub scouts. I rarely sit!!
I keep a stash of Quest bars and EAS Carb AdvantEdge ready-to-drink shakes in my desk at work. That way if I forget to throw a packet in my lunch bag, or if I am suddenly going to eat a late dinner and need my snack earlier in the evening, I have something I can grab.
I cook up 2 or 3 chicken breasts on Sunday to keep in the fridge. Usually i'll just roast them or poach them, and portion out into single servings. On days when I drive straight from work to school for an evening class, I dice up one portion of chicken, and slice up cucumbers and peppers for a dinner that I can eat in the car. The chicken can easily be reheated for a quick dinner at home too, with a side of frozen veggies!
I also make a big pot of veggie soup on the weekend and freeze in single servings for a quick lunch. Especially this time of year, I LOVE soup! I chop up 8 cups of soup veggies (some combo of mushrooms, onion, canned diced tomato, turnips, celery and zucchini), add 4 cups of broth (usually homemade), and when it's cooked I know I have 4 portions of 2 cups veggie each if I divide it up evenly.
Shakes are super portable, and adding mixes to coffee can ensure you get a packet in while sipping your joe over a project or in a meeting
I do alternatives, and Nashua has a few cappuccino mixes that are staples in my arsenal.