I used to do 12 hour days- easiest thing to do is once a week pick a day to bake and cook. For breakfast I used to do baked oatmeal into a cake- for 6 serves, use 2 cups oatmeal or oat flour (the 2 cups just ground into flour), add 4 ripe mashed bananas, a tsp vanilla essence, baking powder, 1/4 cup of either nut butter or coconut oil, and anything else you want to add such as chopped nuts, chia seeds, cocoa powder. For extras add around 1 tbsp. per serve (so 6 tbsp. worth for 6 serves) Also add around a cup of water. Combine the wet, and in a separate bowl combine the dry, then mix together and bake in a cake tin at 180C for around 30 mins. Turn it out, let it cool, then wrap individually in plastic and freeze. At night, pop one in the fridge or on the counter so in the morning it's defrosted and ready to go. Easiest way to get in oats!!
Things you can make ahead for lunches and dinners- a crock pot will be your new best friend. In the morning before work, throw in 4 serves of your meat of choice and ANY veg (chopped celery, carrots, spinach leaves, fresh chopped tomatoes, cauliflower, broccoli etc) Around 5-6 cups worth, season with a few cloves of garlic, some onion, salt and pepper, chilli, herbs etc. Every combination of this works, go crazy! Turn it on low before you leave the house and when you get home you have dinner for 4 days. Serve with rice or quinoa.
Other things you can make ahead- meatballs (here's a recipe I use for chicken breast meatballs; http://www.lucysfitlife.com/?p=397) Make in bulk, divide into serves and freeze anything you won't eat within a day or two. For lunches the night before throw together a salad and serve with rice or quinoa. Frittatas- basically a heap of cooked veg, meat, and 2 eggs for every serve you are making. Bake it all in the oven, cut up and freeze for easy lunches. If you're short on time, the night before make an omelette- 2 eggs, tuna, beans, chopped veg. I buy tins of tuna and bean mix which are great- an even QUICKER meal is grabbing a single-serve salad pack from the supermarket and adding the tuna and beans to it. Presto, meal! Casseroles, rice dishes and pasta dishes all freeze really well as do most vegetables and meats that haven't been frozen before. Planning meals a week ahead makes life easier. There's plenty you can do, most of that stuff you can double up for dinners too. Just make sure you're getting a lot of variety.
For exercise, 3x 30mins a week for strength training is plenty as long as you are targeting all your major muscle groups. Really it just requires getting up 30-45mins earlier 3x a week which is doable!