I find the thought that this earth has nothing to be desired besides God to be an amazing one. We all have desires for our life here and for the lives of our loved ones. But what is the main and most important desire? God and God alone.
We may lose everything we love on earth through war, sickness or other circumstance, but we have God. And He is enough.
The verses go on to say, "My flesh and my heart may fail, but God is the strength of my heart and my portion forever.
Gill's Exposition of the Entire Bible
My flesh and my heart faileth,.... Either through vehement desires of communion with God deferred, see Psalm 84:2 or through afflictive dispensations of Providence, being smitten and chastened continually, Psalm 73:14, or through inward trials and exercises, by reason of indwelling sin, temptations, and desertions: or rather the words are expressive of the body being emaciated by sickness and diseases; and the heart fainting through fear of death, or rather failing at it, being at the point of death; the heart being, as philosophers say, the first that lives, and the last that dies:
but God is the strength of my heart, or "the rock of my heart" (h); when overwhelmed with distress through outward trouble, or in the lowest condition with respect to spiritual things; when grace is weak, corruptions strong, temptations prevail, and afflictions are many; then does the Lord support and sustain his people, and strengthens them with strength in their souls; and in the moment of death, by showing them that its sting is taken away, and its curse removed; that their souls are going to their Lord, and about to enter into his joy; and that their bodies will rise again glorious and incorruptible: