Ecclesiastes 12:1 says “Remember now thy Creator in the days of thy youth, while the evil days come not, nor the years draw nigh, when thou shalt say, I have no pleasure in them;” God tells us it it better to begin serving him when we are younger and still have your youth. This is true for many reasons. Right now we are sowing and one day we will have to reap what we sow (Galatians 6:7-8). We will have to answer for our choices. Starting early makes this easier and more beneficial.
As we get older, age begins to get the best of us and it gets harder to serve the Lord for certain reasons. Ecclesiastes 12:2-8 list these reasons in a metaphorical way. Reasons such as worsening vision, hearing, losing teeth, becoming frail, etc.
So what can everyone take from this passage, young and old? We know that our whole purpose is fear God and keep His commandments (Ecclesiastes 12:13-14), so we must do whatever we can while we are still able. Young and old alike. We must always remember our Lord.