I usually rely on two options. They require some prep and planning, but not much.
I keep blueberries and spinach in the freezer. I defrost them (only a small handful of spinach) in the microwave. I add them to a scoop of a big batch of steel cut oats and cinnamon i've cooked and kept in the refrigerator. I also add walnuts and almonds. If I have some yoghurt, I'll add that. Maple syrup if I'm feeling decadent.
Put a pan on the stove. Add some olive oil and turn heat to medium. Take spinach, cauliflower, onions and peppers from packages in the freezer and throw in pan. Also in the freezer is sausage I've pre-cooked and diced. Toss a handful of that in the pan, too. Add other leftover stuff in refrigerator if you have it. Could be meat or vegetable. Maybe part of a baked potato or sweet potato (I cook extras to use for many meals). Smoked paprika and cumin are my go-to seasonings. Finish with a few eggs--scrambled with the above or over-easy once the pan's empty.