'Abdullah ibn Mas'ood (may Allah be pleased with him) reported that he heard the Messenger of Allah (bpuh) say:
"Whoever transforms all of his concerns into one concern only - concern for the Hereafter - Allah will satisfy his demands and needs in this life. As for he who devotes his concerns to worldly matters, Allah will not care in which valley he perishes."
There are two factors that help one lead a happy life:
1. Moderation in anger.
2. Moderation in fulfilling one's desires.
One has to be moderate in fulfilling his desires, lest his desires and lusts increase to the point of constantly seeking to be satisfied, an outcome that will lead to his destruction. The same can be said about anger, for it too can lead to destruction.
What is required in all affairs is moderation. Strength, when in excess, makes violence and killing easy. And yet if there is a shortage of it, one will not be able to defend oneself against transgressors. But when one uses strength moderately, he can display the qualities of patience, bravery, and wisdom, each in its proper place and time. The same goes for desire; if there is too much of it, then wickedness and licentiousness will prevail; if there is too little of it, then one will become weak. However, if it is present in due moderation, one will achieve both chastity and satisfaction.
"Upon you is to follow the guidance of moderation.""Thus We have made you a middle nation, so that you may bear witness over all humanity, and the Messenger (Muhammad) shall in turn bear witness over you". Surah 2 - Al-Baqarah (143)
ADDENDUM
Attention is drawn to the historic phenomenon that nations which attain ascendancy and supremacy usually display arrogance and conceit, and look down upon other weaker nations. Today's domineering vain-glorious civilization, which has encompassed both east and west, is a vivid living example - a culture of decadence and gross injustice thriving on the great achievements and glory of a genius elite who have split the atom and made inroads into outer space. When the Muslims were a leading nation, however, and at the height of their achievement, they were overwhelmed by a sense of submission to God and a need for His support and guidance. They have always sought God's forgiveness and looked up to His grace, praying:
Our Lord, do not take us to task if we forget or make mistakes,
Our Lord, do not lay upon us a burden such as You had laid upon those before us,
Our Lord, do not burden us with more than what we can bear.
Pardon us, forgive us our sins, and have mercy upon us.
You are our Lord,
Grant us victory over the unbelievers.
Surah 2 - Al - Baqarah (286)