Death is something nearly everyone fears and dreads - and yet it is for our benefit.
I infer that this means that there is, for each of us, a 'time-to-die' - and our challenge (everybody's challenge) is to recognize and accept this time-to-die, when it comes it us or to someone we love.
In a deep sense we are born to die - that is, dying is the primary task of our life and the one task which everybody will accomplish.
We die so that we may be resurrected and move to a higher and more divine state; so if we were not to die we would fail to reach this higher state: and that would be the greatest tragedy and suffering.
To want not to die, to yearn for immortality in this life, is thus a sin - it is a profound rejection of God's plan.
Luke 7: For I say unto you, Among those that are born of women there is not a greater prophet than John the Baptist: but he that is least in the kingdom of God is greater than he.
This means that the least person who dies and is resurrected to salvation will be greater than the greatest Man that had lived until the time of Jesus - greater than Abraham, Moses, David or John the Baptist... than any. I extrapolate this also to suggest that the same applies to even the greatest Saints who have lived since Christ - in reference to their greatness while yet mortal Men (although not in reference to their ultimate stature in Heaven).
So it represents a really colossal error to want never to die, to crave immortality in your current incarnation - or even to want to extend life beyond the proper time-to-die. Because it can be done, and it does happen, and not infrequently - people can and do live beyond the proper time-to-die - and that is why the temptation is real.