But notice: that doesn't cause Moses to despair. He knows about—and has tasted—the goodness of God as well. And that's what launches him into the petition phase of his prayer. Verse 12: "So teach us to number our days, that we may apply our hearts unto wisdom." In other words, help us to keep both the brevity of this life and the realities of eternity in perspective, so that we can be truly wise people.
And then Moses pleads with God for compassion: "Return, O LORD! How long? Have pity on your servants! Satisfy us in the morning with your steadfast love, that we may rejoice and be glad all our days." (vv. 13-14).
Moses realizes that even though he can't erase the consequences of his sin, his life isn't hopeless. He's not dreading what's ahead or seeing the future with a grim outlook at all. He knows the mercies of God are inexhaustible, and God abundantly pardons. God can restore even the years that the locust has eaten. So Moses prays for a special outpouring of God's blessing. Verse 15: "Make us glad for as many days as you have afflicted us, and for as many years as we have seen evil."
In other words, Give us blessing at least equal to our trouble. "Let your work be shown to your servants, and your glorious power to their children. Let the favor of the Lord our God be upon us, and establish the work of our hands upon us; yes, establish the work of our hands!" (vv. 16-17).
God answered that prayer. The work of Moses' hands was certainly established. His life's work was by no means wasted. And he wasn't kept out of the Promised Land forever. Because at the transfiguration, when Christ revealed His glory, Moses and Elijah were there, talking with Him. Moses got blessing equal to his trouble—and infinitely more. After all, God was His dwelling place—and God is a better dwelling place than the land of Canaan.
That's the whole point of Psalm 90. We are dying creatures. Our earthly comforts are few and they are only temporary. This life is going to end shortly. And even if you die of old age, it's a long process of decline to get to that point. The very best you can hope for is that your life will end like a drawn-out groan.
But if God is your dwelling-place then you have an eternal habitation, because He Himself is eternal. Not only that, if God is your dwelling place, then He can bless you even in this sin-cursed world. He will even bless you more than the days you have been afflicted. Certainly, the blessings of heaven are infinitely greater than all the miseries of this life combined.