“So teach us to number our days, that we may apply our hearts unto wisdom.” (Psalm 90:12, KJV)
Wanting to understand what the psalmist means by the exhortation to number my days, I searched the internet. I discovered Noah Millman’s D’var Torah: “Teach Us To Number Our Days” which I recommend you at least skim or speed read, particularly the part about the omer and the counting of days. I can’t begin to explain this practice, but this article adds light to the verse beyond the obvious interpretation — i.e. that we should recognize we are finite and make good use of our time.