If you're willing to put in the work, nothing is impossible.
Tips
usage
肯 (kěn) here means 'willing to' (not 'must' — that's a separate sense). Often paired up: 能吃苦肯干 (néng chī kǔ kěn gàn) 'able to take hardship and willing to work' is a stock phrase in job ads and praise. Slightly informal/spoken.
memory
肯 = 'willing,' 干 = 'do/work.' 'Willing-to-do' = hardworking. Compare with the related 能干 (nénggàn, 'capable, able to do things') — 肯干 is about willingness, 能干 is about ability.
