Juvenescence is a noun that refers to the state or period of being young.
The latin word juvenis (YOU ven ees) which means ‘young’ is the basis for the word juvenile as well as the basis for our word of the day which entered the English language in the early 19th century.
If I had been more determined to prepare for the future, I would have spent my juvenescence keeping up with the latest technology. But instead I spent my youth playing guitar and keeping up with the latest music videos.