be conscientious and do one's best 兢兢业业

“兢兢业业”，汉语成语，形容做事小心谨慎，工作认真踏实。可以翻译为“be conscientious and do one's best，be assiduous或be very careful to do one's work properly”等。

例句：

多少年来，他工作一直兢兢业业。

He'd been doing his job conscientiously for many years.

他更加谨小慎微，兢兢业业，以尽力获得上级的认可。

He was even more cautious than ever, and did his utmost to win the trust and favour of the superior.