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
Magdalene	mahk-dah-LE-nə (German), MAG-də-lən (English), MAG-də-leen (English)	German, English, Biblical, Biblical Latin, Biblical Greek
ZdeŇKa	-	Czech
LÉOnard	-	French
Lauretta	-	Italian
Jurryt	-	Frisian
Babatunde	-	Western African, Yoruba