"Show me, LORD, my life's end and the number of my days; let me know how fleeting my life is." (NIV)
Lord, make me to know my end and [to appreciate] the measure of my days--what it is; let me know and realize how frail I am [how transient is my stay here]. (AMP)
LORD, make me to know mine end, and the measure of my days, what it is: that I may know how frail I am. (KJV)