Chinese (& Thai etc) food is your friend here. Cook a good-sized pot of (brown) rice, which will keep in the refrigerator for a week or so. Meat & veggies can be chopped ahead of time, and can be kept in containers in the fridge (meat in the freezer if it's for more than a day or two). A bit of oil in the wok on high heat, add meat, stir-fry until browned, add veggies and a bit of sauce, stir-fry a minute or two more. Meanwhile you've put a serving of rice on a plate and stuck it in the microwave for a minute. Dump the contents of the wok on the rice, and enjoy. (Or depending on appetite, eat half or a third of it now, put the remainder in the fridge to zap later.)
Also quick quesadillas: for each, two tortillas, 2-3 slices of cheese (I use sharp cheddar and mozarella or asiago), a couple of green onions, 1/4 green pepper, 1/4 jalapeno pepper, and a bit of leftover chicken, turkey, beef, or whatever. Break the cheese into smaller chunks and distribute around 1 tortilla. Chop the veggies & meat, and do likewise. (Chopping can be done beforehand.) Put in a large pan over medium heat, cover, and heat for a minute or so until tortilla turns brown in spots (but not black), then flip and repeat on the other side.