If you've had any sort of physical activity, protein would be a good idea. Eggs are protein-rich and nutrient-rich. Green veggies should rock your plate at every meal and breakfast is no exception - Whether you're a green smoothie type of person or a sautée-my-spinarch, the fiber, nutrients and the cooking fat with keep you full for a long time. On the go, nuts will work in a pinch. In fact, legendary coach Charles Poliquin recommends a meat&nuts breakfast.

I advise against juice, as it is mostly sugar and not really nutrient-dense. Fruit is... Okay I guess, certainly not better than a protein source and greens.

Hope it helps!

Vincent