작심삼일이 · 작심삼일을 (often 작심삼일로 끝나다)
resolutions that don't last; giving up after three days
Example
새해 다이어트 계획이 또 작심삼일로 끝났어요.
My New Year's diet plan fizzled out after a few days again.
Word parts
작 make+심 mind+삼 three+일 day
Literally 'a made-up mind lasts three days'.
Good to know
Usual pattern: 작심삼일로 끝나다 'to end as a three-day resolution'.
Related words