be on (one's) mettle

To be determined to succeed and thus prove one's worth, often in a difficult or unpleasant situation. I know my employees think I'm too young to be their supervisor, so I have to be on my mettle every day at the office.

Common Names:

Name	Pronounced	Usage
Rex	REKS	English
Ewart	YOO-ərt	English
Zoe	ZO-ee (English), DZO-e (Italian)	English, Greek, Italian, Ancient Greek
Zakariyya	-	Arabic
Idir	-	Northern African, Berber
Arabinda	-	Bengali, Indian, Odia