In the first part of the second part of the Summa, Aquinas goes through all the things men turn to in their search for happiness and shows why they all fail. You can read through them here.
Here's a quick summary of each article written by Msgr. Paul Glenn that I think you'll find helpful. Right to the point and clear.
I won't get into what will make us imperfectly happy in this lfie or perfectly happy in the hereafter, we'll just stick in this article to all the things that don't work.
Wealth
Man's happiness is not to be found in wealth, whether this be natural wealth which serves his normal needs (such as food, clothing, housing), or artificial wealth which can provide the items of natural wealth, that is, money. Wealth of any kind is a means for acquiring something else; it is a thing that serves; it does not fulfill. Hence it cannot be the true last end of man and the object that will render him enduringly and completely happy.
Honors
Nor can man's full happiness consist in honors bestowed because of some excellence in him. Any excellence in a man is in him by reason of some good already possessed; it means that he already has some degree of happiness. Honors come to him because of this happiness, and therefore honors cannot themselves be the constituting elements of perfect happiness.
Fame and Glory
Nor can man's happiness be found in fame and glory. These, like honors bestowed, presuppose some degree of happiness already attained, and this they publicize and praise. Fame and glory are consequent upon an imperfect happiness, and are, in some sense, the product of it. They cannot, therefore, be the essential elements of perfect happiness.
Power
Man's perfect happiness cannot consist in the possession of power, for power is not a complete end, but a means; power is valuable according to the use to which it may be put. In a word, power looks on to something further; it cannot itself be the ultimate goal.
Goods of the Body
Man's ultimate happiness does not consist in goods of the body - life, health, strength, beauty, agility, etc. - for these goods preserve the body and its perfections. Merely to preserve life cannot be the end of life. Goods of the body are to be used by reason (intellect and will) somewhat as a ship is used by its master; the master does not use the ship merely to preserve the ship, but to carry profitable cargoes to desired ports. Thus it appears that the goods of the body are means, not complete ends. Besides, man is a rational being as well as a bodily being; he can never be completely fulfilled and satisfied by bodily goods.
Pleasure
Pleasures, whether bodily or intellectual, cannot bringa man ultimate happiness. We have just seen that bodily things cannot be man's perfect fulfillment. And mental enjoyments presuppose the end already attained; enjoyment follows upon possession of some good or end; what is consequent upon the end cannot itself be the end.
Goods of the Soul
The goods of the soul - its essence, faculties, acts, habits, perfections - cannot constitute man's ultimate end. Happiness is for the soul, and to be attained by the soul. The objective ultimate happiness is something outside the soul, which the soul seeks to bring into itself and possess subjectively. Hence this ultimate end is not the soul itself, nor the goods belonging to the soul.
Indeed, no created good can give man perfect happiness. Only the essential, universal, and boundless good can bring man complete and unfading fulfillment. No created good is universal, essential, and boundless; only the uncreated good can be the ultimate end of man. And this uncreated good is God.
