Every one of the geezers who continues to play a leadership role has one quality of overriding importance: neotony. The dictionary definition is that neotony, a zoological term, involves "the retention of youthful qualities throughout old age." It is more than merely retaining a youthful appearance, although that is often part of it. Neotony is the retention of all those wonderful qualities that we associate with youth: curiosity, playfulness, eagerness, fearlessness, warmth, energy.
Neotony is a metaphor for the quality of life - the gift - that keeps the fortunate of whatever age focused on all the marvelous undiscovered things to come.