live day to day; take things as they come; not plan ahead
Proverbial expression meaning one is too busy with immediate concerns to plan for the future; often carries a nuance of resigned acceptance or carefree attitude. Literally 'in the morning, one does not plan for the evening.'
He lives day to day with the attitude of not worrying about tomorrow.
The proverb 'Asa ni yūbe o hakarazu' describes a state of being too preoccupied with the present to plan ahead.
明日は明日の風が吹く is a more optimistic, forward-looking proverb meaning 'tomorrow will take care of itself,' whereas 朝に夕べを謀らず can imply a more resigned or overwhelmed state.
A Japanese form of the Classical Chinese expression 朝不謀夕, literally “in the morning, not planning for the evening,” used of living without assurance or provision for the immediate future.