Wondering how advancing years and the accumulating evidence that decrepitude will move into our bodies more and more affects Christians differently than it might someone with a less settled outlook

…Is merely imagination.
 

Just as people are destined to die once, and after that to face judgment, so Christ was sacrificed once to take away the sins of many; and he will appear a second time, not to bear sin, but to bring salvation to those who are waiting for him.
 
Hebrews 9:27-28

(Universalists, please note the middle and latter parts of that – it doesn’t say merely “take away sins” nor “take away the sins of all”. To whom he brings salvation is also specified.)