When you are young, there is the illusion you will live forever.  Every one knows you will not leave this earth alive.  But we act as if this should never happen.  Death has become the last taboo.

When you become older and your body starts to break down, this illusion starts to break down.  Death becomes more of a reality.  Of course, this may occur when you are young too.

Of course, when you become older and the realization your time is running down (???) it may sharpen your search for meaning.  You might stop spending time on things that really do not matter in the long run.

And spend it on the things that really do matter.  Time is finite.  And death or old age brings this to a head and may force you to face issues maybe you have avoided.

Every decision we make means you can not do something else.  We have to choose.  We can not live without dying.  And the realization of death sharpens that.