Spiritual hunger and thirst is that insatiable craving after spiritual things that can be characterized by the attitude of a starving man in the physical realm.

How do we develop a spiritual appetite? The solution is EAT.

Exercise - the process of spiritually allowing the nourishment you have to be turned into muscle rather than fat.

Ask - the process of securing from God both the appetite and the capacity for spiritual truth.

Taste - the process of personally experiencing the righteousness of God.

Incidentally, that righteousness in itself creates the hunger for itself.