Do you ever prepare breakfast the night before and if so, what?

Always eat breakfast before exercise. You don't want to be unbelievably week after doing exercise – that's not the point.

Not really. For breakfast I mostly eat something simple like cornflakes and milk or a simple sandwich and drink a cup of jogurt.

Yes, I have a kilner jar and I make overnight oats.
Oats, fill the jar up half way, fill it with water or milk, then raisins, seeds, nuts or peanut butter (any healthy Toppings)
Leave them in the fridge for the night and voila.
Also, I sometimes cut up fruit and vegetables the night before to snack on in the morning.
Or you can take out some ingredients for a smoothie or healthy milkshake or juice and cut what you need to cut, and just plop them in the blender in the morning. 🙂