In old age we reflect on our life with a mixture of highs and low but with a profound sense of thankfulness. King David did not enjoy a happy retirement. David sinned and brought down a great plague on his people. He ended his days bed-ridden and powerless with plots afoot. There were elements of David’s experience that set the pattern for God’s ultimate king, Jesus. This song is cited by NT writers more than any other. In one way or another all of God’s people can expect to face similar challenges. This then becomes their song as the birthdays mount up.