You don’t have to eat a large breakfast, but some protein at least is good for “breaking your fast”. Sometimes I’ll have a cup of fat free or low fat cottage cheese with 6 oz of fresh berries (plus water, tea, milk, lots of fluids). Most berries come in 6 oz plastic clam shell packaging so there’s no measuring to do. I also need lactose free cottage cheese and add Stevia (natural sweetener) to sweeten the berries. It’s almost like eating dessert! Other times, I will have 98% fat free yogurt but it isn’t always enough or very hearty. Oatmeal with fruit will stick to your bones! And of course, there’re eggs, toast, bacon, pancakes, etc. I stay away from most cereals because of the added sugar and other stuff like preservatives. I hope this has been helpful.
I have branflakes and a bannana.
I also make a big skillet of potatoes, mixed vegetables, sausage, ham, etc. and freeze individual portions. Great by itself or you can add a fried egg, avocado, salsa on top. Or premake breakfast burritos and freeze them too.
Basically, get all the cooking out of the way because you're not going to want to do any of it in the morning. Make it super easy on yourself.