Age is just a number. People say it’s the basis of a person's maturity and retirement, but is it really the basis of retirement—the end of service? Of course not. In fact, in the Scripture, we learn from the life of Abraham and Sarah that even in their old age, the Lord used them for a greater purpose.
Abraham was 100 years old and Sarah was 99. Clearly Sarah had already passed the age of bearing a child. She laughed at the thought of having a baby. She laughed at the thought of her and Abraham running after a child. But just as God promised them, they had Isaac.
God promised and He is a promise keeper.
Even though Sarah doubted at first, we can see that if you are willing to be used by God, no matter how old you are, He will use you mightily. Serving God does not require age, it only requires willingness and commitment to do His work.
When I was young, I saw the deacons and the church members serving the Lord even at their old age. I looked up to them, and I told myself that someday I want to be like them. Even when my hair turns gray, when my eyesight fails, and when I get wrinkles, still I will let God use me according to His will and purpose in my life.
Age will never be a hindrance in serving God. Just like Abraham and Sarah, God used them mightily despite their old age. God promised Abraham that he will be the father of a great nation then God fulfilled it at the right time. Not too late, not too early, just at the right time.