vitality
n. uncountablen. the state of being strong, active, and full of energy. It is the feeling of being truly alive and healthy.
n. the state of being strong and active; energy. Often refers to the power of a living thing to continue its existence or the capacity of an abstract concept to remain effective.
Regular exercise can help you maintain your vitality.
The new park has brought a sense of vitality back to the aging neighborhood.
Economic analysts expressed concern that the aging population might eventually sap the nation's economic vitality by reducing the size of the active workforce.
From vital + -ity, from Middle French vitalité, from Latin vitalitas (“vital force, life”), from vitalis (“vital”); see vital.
Uncountable in its general sense; often used with 'of' to describe the energy of a system or person.