Two Thirds of a Long Life

When can you be said
To have lived enough
To not be mourned overmuch
After you’re finally dead?

Imagine generations
Of humans born expecting
To get to two-score and ten,
Any one of them amazed

And frankly lonely to find
Life carrying on
At fifty-eight, fifty-nine.

Would that be any different
Than our centenarians
Bemused to still be present?