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
Caecilius	-	Ancient Roman
Adara	-	Hebrew
Inka	EENG-kah (Finnish), ING-kah (German)	Frisian, Finnish, German
Annora	-	English (Rare)
Rizwan	-	Urdu, Arabic
Bullock	['bulək]