Numbering our days in hope

It seems the Psalmist more than once asks to know the number of his days.  In Psalm 39: "Lord, let me know my end and the number of my days..."  The Psalmist contemplates vanity and the shortness and insubstantiality of human life.

"Truly even those who stand erect are but a puff of wind." (Psalm 39:6)

The question naturally arises, where is our hope?

"O Lord, my hope is in you." (Psalm 39:8)

The insubstantiality of human life is contrasted with the hope (and weight) of glory.