vigor
n.physical or mental strength and energy. You use this to describe someone who works or acts with a lot of power and focus.
n.physical strength and good health; the capacity for survival or continued growth in a biological or social context. Often associated with robustness and active force.
“She started her new job with great vigor.”
“The plants grew with surprising vigor after the gardener added the new fertilizer to the soil.”
“The committee debated the proposed reforms with renewed vigor, determined to reach a consensus before the legislative session concluded at the end of the month.”
Commonly follows the preposition 'with'. In British English, the word is spelled 'vigour'.
“The semi-fictional tale is about Maddie’s befriending of the 87-year-old Darcy O’Shea, an artist and piano teacher 50 years her senior, who is full of zest and vigour.”
“The performances are pointed and everyone tells their strange or silly tales with vigour, so that storytelling itself becomes a reason for continued existence.”