We trust in the Lord, as far back as our birth, and He has cared for us. We never stop praising Him, giving Him glory all day long.
Then, as old age comes upon us, He does not abandon us when our strength is failing. Even if our enemies are plotting against us, telling lies that God has left us and cannot help us, we know it is all lies.
Some of us may not be skilled in words, but we praise His glory anyway.
In some Bible versions of this same psalm, Psalm 71 is known as the "prayer of an old man for rescue." But one's age may not be considered old in terms of physical age. My wife passed away at the young age of forty-seven. And even though it was young in both her's and my eyes, the strength in her body was failing, along with her mind, but one thing was as strong as ever: her faith.
The Lord is our Rock. Protector. He guides us through life, through troubled waters, and will always lead us to the glory that is Heaven.