Do not cast me off in the time of old age; Do not forsake me when my strength fails. (Psalm 71:9)
The psalmist knew that as he aged his vigor and strength would not remain as in the days of his youth. He was not praying to be preserved; he was praying that his usefulness would endure. The lessons here are simple: Take advantage of your youth. Give your best while you have it to give. Utilize your strength while your strength prevails. There will come a day when the spirit remains willing, but the flesh will be weak. Do not waste your youth on youthful lusts. Take advantage of your physical and mental sharpness. It will not always be faithful to you. However, even when you are growing older, continue to seek the strength of the Lord. Use the wisdom of your years to instruct those who do not have the experience of time on their side. Serve the Lord in your youth, and hold on to him in your prime time years.