Therefore do not worry about tomorrow, for tomorrow will worry about itself. Today has enough trouble of its own.
Halfway through brushing your teeth, your mind can slip ahead into next week's meeting, already rehearsing what you'll say if it goes badly. By the time you rinse, you could have solved three problems that haven't happened and found two new ones. Underneath it all sits a quiet rule: I have to solve tomorrow today, or it will catch me unprepared.