A 'Proper' breakfast -Everyday.
Being diabetic I have to do it - but then I did it as a 'normal' person too.
For me - two sorts.
Monday/Wednesday/Friday- gym day - a work out from just after 8 till 930.
Cereal[porridge or shred wheat no sweetener] toast and preserve honey coffee.
All other days skip the cereal -fruit[banana etc.,]toast / coffee
just got to do it.
If I don't I am about ready to fall over come mid morning.