en·er·gy

ˈenərjē/

noun

1. 1.

   the strength and vitality required for sustained physical or mental activity.

   "changes in the levels of vitamins can affect energy and well-being"

   synonyms:vitality, vigor, life, liveliness, animation, vivacity, spirit, spiritedness, verve, enthusiasm, zest, vibrancy, spark, sparkle, effervescence, ebullience, exuberance, buoyancy, sprightliness;