Shlomo Hamelech describes the difference between a ba’al bitachon and someone without. צדיק אוכל לשבע נפשו, ובטן רשעים תחסר – A righteous person eats to satiation, but the belly of a wicked person is lacking. (Mishlei 13:25)
A tzaddik who has food for today doesn’t worry about tomorrow. He eats what he has now until he is full and knows that with bitachon he’ll have what he needs tomorrow also. He has nothing to worry about today.
But someone who relies on his own effort is never satisfied. He won’t eat all that he has today because he’s nervous he won’t have tomorrow. That’s why his stomach is never full, he’s always scrimping and saving for a “rainy day.” No day is lived to the fullest because he always has the fear of the future in his mind.
When you have bitachon, every day and any situation is the same. If you have what you need now, enjoy it. Hashem will make sure you have your needs tomorrow as well.