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
Aila	-	Finnish
Uilani	-	Hawaiian
Brigham	BRIG-əm	English (Rare)
Peronel	-	English (Archaic)
Johnathon	JAHN-a-than	English
Djehuti	-	Egyptian Mythology