We use extravagant language when we’re in love and that’s how this reads at first: You are my everything, the apple of my eye, the focus of all my desire.
But the psalmist isn’t just expressing the depths of his devotion to God here. He’s reflecting the fundamental nature of reality as personal and good.
The LORD (a personal name for God) is identified as the Lord over the psalmist. This is more than a formal identification – it is the establishing of a weighty relationship with rights, obligations, respect and love.
All that is good comes from God as the creator of all that is. Flowers are beautiful, that is, because God rejoices to make them that way. More than that, as Psalm 16 emphasizes, God protects his people particularly. Because of this relationship, all of the particular goods the psalmist receives he can simply identify as from God.
This cry of love is part of the psalmist reminding himself of all God’s blessings. To me it reads as someone assuring himself in a difficult time. If the Creator, the foundation of reality, is a person that you can call ‘my Lord,’ we can be certain his love will preserve us.