If there is a common desire in this world, is the desire to be happy. From the birth to the end we search, sometime desperately, our happiness, our joy.
The drama is that we take the wrong way and then, in the place to reach the dreamed goal of happiness, we finish in the opposite side: sadness, depression, desperation.
Another general experience is that our joy is bound to love. If we feel loved we are basically satisfied and still more if we are able to love.
What many people are not understanding, is that all these things (life, happiness, love) are strictly coming from the source of our life. Who is God Himself. The more a person goes toward God, the more lives in communion with Him, the more finds himself, the more finds the real roots of his being and satisfy his deepest desires. The more the human person cut his relationship with God and goes far from Him, the more spoil his existence going toward nothing, nonsense, desperation.
St. Augustine, who experienced in his life everything, finally confessed in the book, called just "Confessions": "You have made us for Yourself, and our hearts are restless until they rest in You". Many surely experienced the complaining of God about his people, written by the Prophet Jeremiah: "My people have committed a double crime:/ they have abandoned me,/ the fountain of living water,/ only to dig cisterns for themselves,/ leaky cisterns/ that hold no water" (Jr 2,13).