Cereals with milk, one fruit and a glass of water.
1-2 boiled eggs, a glass of water and a cup of coffee.
Sandwich one fruit and/or a glass of orange juice
Then I bring a smoothie and/or a protein bar. If possible, I wait with eating those until I’ve reached my destination. If that takes too long, I’ll eat them on the train.
another good idea might be a bulletproof coffee, a very popular keto breakfast you can find many recipes for online. since its a liquid its really easy and convenient for on the go too. i havent tried it myself but two friends of mine are big fans of it.