"For God alone my soul waits in silence; from him comes my salvation.
He alone is my rock and my salvation, my fortress; I shall never be shaken."
What would it take for you to make those words your own? While not everything in David's life is admirable or praiseworthy, his single-minded devotion to God certainly is. And his passion for God shines through in the many psalms which he left as the product of his life, a legacy that has long outlived him.
To state that we desire God "alone" is a powerful expression of faith. It sets Him above everything else. It reveals a realization that everything else in this world is fallible and will let us down. (Status and riches are specifically mentioned in verses 9 and 10 as being notoriously unreliable.)
Such faith ought to make a difference in the way we live our lives. Sometimes the conclusion of a psalm does not occur at the beginning or end, but is found in the middle. The theme of this psalm appears to be verse 8:
"Trust in him at all times, O people; pour out your heart before him; God is a refuge for us."
If is it true that God "alone" is enough for us, we should be found as people who will trust in him at all times, and find our refuge in him. God alone is everything we need.