Strength and Energy to Keep Going for a Long Time
Puzzle 12 of Christmas Stockings Hard Pack
Question is: Strength and Energy to Keep Going for a Long Time
and the answer is: STAMINA
Word Meaning:
STAMINA — The energy and strength for continuing to do something over a long period of time; power of sustained exertion, or resistance to hardship, illness etc.
Definitions from Wiktionary.