I have fatigue condition as well, so honestly I just gave up on "cooking". Try to aim for "arrangements" instead. Much easier and takes less focus/time/energy.

• Toast with toppings
• Greek yoghurt fruit bowl
• Smoothie
• Canned bean burritos with cheese
• Other healthy snacks
• Etc

Obviously it depends highly on your dietary needs. I'm vegetarian with very complex health so I built my diet around that, but you might have more flexibility. Try not to buy "ready to eat" stuff every day though because they're usually pretty bad health wise. Also the freezer is your friend; it will forgive you when you forget leftovers for 3 months.