Measure of Our Days
Psalm 39:4 (ESV) … “O Lord, make me know my end and what is the measure of my days; let me know how fleeting I am!”
Psalm 39 asks us to think about the brevity of life. The world, by contrast, does not like us to think much at all, especially about such things as life, death, and eternity. Thinking about them spoils the world’s fun and makes us harder to manipulate. The flesh is unable to think about eternal matters, at least on a spiritual level. It cannot understand them because “they are spiritually discerned” (1 Cor. 2:14).
The devil hates us to think and does everything he can to keep us from thinking, especially about the meaning of life and the fact that we must spend an eternity either with God in heaven or without him in hell. Therefore, the world, the flesh, and the devil conspire to keep us amused or entertained.
Don’t make the mistake, that most people do as they drift through life and inevitably pass through the dark doors of death into eternity unprepared. Psalm 39 is a rebuke to such folly. Verse 4 demands that we think about the brevity of life, so we may apply our hearts to wisdom and use the time we do have well. The best use of our time is to make time for Jesus. The threat of death hangs over all human existence and finds relief ultimately only through the resurrection of Christ. “But thanks be to God, who gives us the victory through our Lord Jesus Christ “ 1 Corinthians 15:57.
 Boice, J. M. (2005). Psalms 1–41: An Expositional Commentary (p. 339). Grand Rapids, MI: Baker Books.