Mat 5:6 Blessed are those who hunger and thirst for righteousness, for they shall be satisfied.
The state of blessedness is set aside for those who are not satisfied with where they are spiritually. His longing shall find peace in Jesus Christ the righteous. He shall drink of the living water and never thirst again.
Paul’s hunger, Php 3:10 “that I may know him and the power of his resurrection, and may share his sufferings being conformed to His death, …13 Brothers, I do not consider that I have made it my own. But one thing I do: forgetting what lies behind and straining forward to what lies ahead, 14 I press on toward the goal for the prize of the upward call of God in Christ Jesus. 15 Let those of us who are mature think this way, and if in anything you think otherwise, God will reveal that also to you.” Paul resolved to cleave to, namely, Christ and His righteousness.
There is another aspect of hunger, that is to see justice in unjust world, there is a groaning in prayers for what is wrong to be made right. Psa 89:14 “Righteousness and justice are the foundation of Your throne; Mercy and truth go before Your face.” As one commentary reads, “God is not merely strong to do whatever He wills; but all that He wills is consonant with right and justice”