One of the priceless benefits of a relationship with God is that He satisfies our desires with good things, thus renewing our youth like the eagle.
There is a word in verse 5 which is a little bit challenging to translate. Some translations say "desires". Others say "years". But the most literal translation for the word is "jewelry or ornaments". I believe the idea is that God answers our yearnings. Notice that it does not say he gives us everything we want. But he supplies our yearnings with GOOD things! As the Good Shepherd He will only guide us toward what is good for us. He even works good in all things for us. This brings deep satisfaction to our hearts. The Bible says godliness brings the fruit of peace. And this satisfaction from the good gifts of God also brings about another, and perhaps surprising affect!
It rejuvenates us! In other words it makes us young at heart again. It makes us youthful in a good, not a foolish way. A relationship with God pumps hope, zest and idealism into our lives! Kind of like when we were eighteen years old! This counteracts the growing crustiness of skepticism and pessimism which creeps over most godless people as the years go by. It renews our strength so that we can soar above the world once again. See Isaiah 40. 29-31.