I definitely believe that the hardship of fasting is 90% in your head.
I know for myself, on some Shabbasim I’ll have a cup of coffee in the morning before shul, BUT on MOST Shabbasim I don’t have anything at all until kiddush after shul, around noon, – and it doesn’t bother me at all.
Today I am fasting and I was already STARVING by 10 a.m.