Answer:

stamina

Answer	Crossword Clue
STAMINA	Marathoner's quality
STAMINA	Endurance
STAMINA	Spine

STAMINA	Lasting quality
STAMINA	Marathoner's need
STAMINA	Triathlete's need
STAMINA	Staying power
STAMINA	It's needed to finish a marathon
STAMINA	Fortitude
STAMINA	Lasting power
STAMINA	Legs

STAMINA	Triathlete's asset
STAMINA	10K need
STAMINA	Inner strength
STAMINA	Asset for the long haul
STAMINA	Marathoner's asset
STAMINA	Power of resistance.
STAMINA	Capacity to endure strain.
STAMINA	Staying power.

STAMINA	Vigor.
STAMINA	Endurance.
STAMINA	Asset for a track star.
STAMINA	Endurance factor.
STAMINA	Miler's asset.
STAMINA	Flower parts
STAMINA	Miler's need
STAMINA	Durability

STAMINA	Marathon-runner's forte
STAMINA	Power to endure
STAMINA	What rash dieters lose
STAMINA	Miler's sine qua non
STAMINA	Marathoner's requirement
STAMINA	Strength
STAMINA	Workhorse's quality
STAMINA	Intestinal fortitude

STAMINA	Marathon runner's need
STAMINA	It helps you go the extra mile
STAMINA	Lasting ability
STAMINA	The stuff that marathoners are made of
STAMINA	Triathlete's quality