I think my mother's resilience and cheerfulness contributed in a meaningful way to her longevity.

There is a danger there - a very real danger to humanity. Consider, Watson, that the material, the sensual, the worldly would all prolong their worthless lives. The spiritual would not avoid the call to something higher. It would be the survival of the least fit. What sort of cesspool may not our poor world become?

Nothing is more beautiful than cheerfulness in an old face

As long as there is a chance of the world getting through its troubles, I hold that a reasonable man must behave as though he were sure of it. If at the end your cheerfulness was not justified, at any rate you will have been cheerful.

He makes a July's day short as December, And with his varying childness cures in me Thoughts that would thick my blood.

Had she been light, like you, Of such a merry, nimble, stirring spirit, She might ha' been a grandam ere she died; And so may you, for a light heart lives long.