Answer by Professional Japanese Teacher
Do your best! (Good luck!)
The most common way of wishing someone “good luck” in Japanese is the word ganbatte. Ganbatte also has the meaning of “do your best”.
This is a conjugation of the word がんばる ganbaru, which means to “persevere “or to “persist”. Ganbatte is often used to encourage someone to do his best in his endeavors. It has no direct translation in English. The closest meaning to this word is “加油 jia you” in Mandarin.
However, it is not appropriate to use ganbatte on someone superior, such as your boss. Only use it for your juniors or peers.