Zechariah and Elizabeth were childless, which in their culture was a great misfortune, even a disgrace (since there would be no heirs to carry on the memory of the family). One can imagine their feelings of failure and inadequacy.
All of us feel barren in one way or another. We haven't "produced" in our lives what others (or we ourselves) had hoped we would. Our failure to live up to "what might have been" leaves us with a certain empty feeling.
But God does things through us that we ourselves cannot do, or even measure. And God does them often in ways we don't understand.
That's the secret. Let God what God wants to do through us. That is the path to greatness - no matter what our ages, no matter what our conditions.
O Lord, let us let you do what you want to do through us today.
- Little Blue Book, Diocese of Saginaw