Here's one answer.

In the summer of 1922, the Paris weekly newspaper L'Intrasigeant posed as their "Man on the street" question

"An American scientist announces that the world will end, or at least that such a huge part of the continent will be destroyed, and in such a sudden way, that death will be the certain fate of hundreds of millions of people. If this prediction were confirmed, what do you think would be its effects on people between the time when they acquired the aforementioned certainty and the moment of cataclysm? Finally, as far as you're concerned, what would you do in this last hour?"

The novelist Marcel Proust responded:

"I think that life would suddenly seem wonderful to us if we were threatened to die as you say. Just think of how many projects, travels, love affairs, studies, it -- our life -- hides from us, made invisible by our laziness which, certain of a future, delays them incessantly.

But let all this threaten to become impossible for ever, how beautiful it would become again! Ah! If only the cataclysm doesn't happen this time, we won't miss visiting the new galleries of the Louvre, throwing ourselves at the feet of Miss X, making a trip to India.

The cataclysm doesn't happen, we don't do any of it, because we find ourselves back in the heart of normal life, where negligence deadens desire. And yet we shouldn't have needed the cataclysm to love life today. It would have been enough to think that we are humans, and that death may come this evening."

I suspect that without mortality salience I would have more trouble getting out of bed and doing something useful every morning. Or I would just play games forever.