Why should we want God to teach us to number our days (Psalm 90:12)?

from the old testament

• Psalm 90:12 says, “So teach us to number our days that we may get a heart of wisdom.” Throughout this psalm, Moses contrasts our fleeting lives to the eternal nature of our Heavenly Father. He asks for God to make him and the Israelites aware that their life is brief so they’ll be wise. Considering the brevity of life helps us put it into perspective. It reminds us to make the most of life by keeping our focus on the Lord.
• David requests this same awareness. He implores God in Psalm 39 to “let me know how fleeting I am! Behold, you have made my days a few handbreadths, . . . Surely all mankind stands as a mere breath! . . . And now, O Lord, for what do I wait? My hope is in you” (v. 4–5, 7). David knows his life is short and that sin is always a temptation. That’s why he prays in that same psalm, “Deliver me from all my transgressions” (v.8). He wants God to remind him of the transience of life so he can focus on doing God’s will during his time on earth.
• David’s son also realized what was important in life and expresses it in Ecclesiastes 12:13–14: “The end of the matter; all has been heard. Fear God and keep his commandments, for this is the whole duty of man. For God will bring every deed into judgment, with every secret thing, whether good or evil.” Solomon had every earthly pleasure we could imagine: power, wealth, relationships, the best food and other comforts. But in the end, he realized that “all is vanity” (Ecclesiastes 1:2). Nothing he had would last forever. He concluded from all his wisdom that we should “Fear God and keep His commandments.” Only following the Lord gives our brief lives purpose and meaning.
• As in Psalm 90, Isaiah 40:6, 8, focuses on the impermanence of everything except God: “All flesh is grass, . . . The grass withers, the flower fades, but the word of our God will stand forever.” Nothing and no one on the earth lasts forever. Only God and His Word are everlasting. The contrast reminds us to keep our focus on what is eternal rather than what “withers” and “fades.”

from the new testament

• In Luke 12:16–21, Jesus relates the parable of a rich man who had so much that he planned to build larger barns and revel in his “ample goods” so that he could “relax, eat, drink, be merry.’’ Jesus says, “But God said to him, ‘Fool! This night your soul is required of you, and the things you have prepared, whose will they be?’ So is the one who lays up treasure for himself and is not rich toward God.” The rich man’s heart was bent toward the pleasures of this life rather than God. He wanted to enjoy a selfish, hedonistic lifestyle without giving thought to the Provider of it all. The rich man didn’t “number” his days.
• Gaining a “heart of wisdom” by realizing life’s brevity includes an awareness that pleasures and pains are fleeting. In 2 Corinthians 4:16–18, Paul writes, “So we do not lose heart. Though our outer self is wasting away, our inner self is being renewed day by day. For this light momentary affliction is preparing for us an eternal weight of glory beyond all comparison, as we look not to the things that are seen but to the things that are unseen. For the things that are seen are transient, but the things that are unseen are eternal.” Persecution is temporary and develops our character, preparing “us for an eternal weight of glory.” Keeping our eyes on Jesus helps us realize that persecutions, like everything else in our earthly existence, are temporary.
• James realized how brief life is and how foolish it is to focus on plans that have no lasting value: “Come now, you who say, ‘Today or tomorrow we will go into such and such a town and spend a year there and trade and make a profit’— yet you do not know what tomorrow will bring. What is your life? For you are a mist that appears for a little time and then vanishes. Instead you ought to say, ‘If the Lord wills, we will live and do this or that’” (James 4:13–15). James cautions readers against worldliness and lack of humility. Those who make plans as if God has no say in them will soon realize their mistake. We are not completely in control of what path our life will take. We should prioritize the Lord and do His will.

implications for today

Today’s society seems determined to ignore mortality and promote a “forever young” mindset. People spend thousands on cosmetic surgery and topical beauty treatments in a futile effort to hold onto youth. Age and death won’t be put off, though. Far from being a terrifying thought, Psalm 90:12 teaches that acknowledging the brevity of life can make us wise. When we recognize that our time on earth is short, we’ll want to make the best of it by serving the Lord. If a job, relationship, or anything else interferes with our walk with God, we must let it go (Matthew 5:29–30). Those things are temporary; serving the Lord is lasting. Believers should prioritize the spiritual over the material. For example, while Christians should do what they can to help the needy with material goods (Matthew 25:35–40; James 2:16), the priority should be sharing the gospel (Matthew 6:33). When we understand that our time on earth is limited—that our days are numbered—we begin to realize the importance of living those days for God. We become more eager to share the good news of salvation with others (Matthew 28:18–20) and to love others with the love God has for them (John 13:34–35). We learn to "walk by the Spirit" (Galatians 5:16–26) and "sow to the Spirit" and "do good to everyone" (Galatians 6:7–10). Earthly life is a limited resource we mustn’t squander on superficial pursuits. God has His kingdom and eternity in mind, and so should we—but in order to do that, we need Him to teach us to number our days.