The Fountain of Youth was sought by Don Juan Ponce de Leon who was with Columbus on his second voyage in 1493. The New World was thought to be Magical and he heard Indians tell of Bimini, a fabulous island in the North where people lived a long time. He landed by St. Augustine claiming Florida at Easter time. in Spanish "Pascua Florida" (meaning Feast of Flowers) .
Anyway, he Never did find the Fountain of Youth. Most likely a Fountain of Youth is more myth than reality.

Going to suggest that those that live a long time, have Something to Live For. Many of the significant people in history who lived for some sort of Mission or had a Passion for their Work, Lived longer than their contemporaries.

The Fountain of Youth, rather than being something outside, is some Internal Purpose of Life. The purpose of their life is to live a life of purpose. The test to see if your mission on earth is finished. If you are alive, it isn't.

There is a Down side to this: Some were killed for their beliefs as in the lyrics of the song "Abraham, Martin and John". Those who have nothing to Die for, have noting to Live for. The issue is not whether we will die, but how we will live.

Going to leave you with this Cherokee Saying:
When you were born, you cried and the world rejoiced; live your life so that when you die, the world cries and you rejoice.