Seventy years are given to us! Some even live to eighty. But even the best years are filled with pain and trouble; soon they disappear, and we fly away. Who can comprehend the power of your anger? Your wrath is as awesome as the fear you deserve. Teach us to realize the brevity of life, so that we may grow in wisdom. —Psalms 90:10-12 NLT

Psalm 90 includes multiple reminders that humankind is not by nature eternal. The psalmist, identified as Moses in the superscription, noted that it generally takes 70 or 80 years for humans to turn back to dust (vv. 3,10). In light of this, he prayed that God would help his people to number their days (v. 12).
God is eternal. Humans are not, due to their fallen nature. A merciful Jesus interrupts the ordinary nature of things, declaring, “Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent” (Jn 17:3). Only an eternal God could give eternal life. Only an eternal and merciful God would.
God is eternal. Without Jesus’ mercy and LOVE, we will not be able to cross that bridge from sin to salvation. Jesus is my Savior. God is sovereign!
Jesus, in my humanness I cannot understand eternity, but I do not have to understand it to believe in it. Thank you for gifting me with forever.
Teach me, dear Jesus, to number my days. and live it to the full (glorifying You, my God).
Amen.