“Happiness or sorrow- whatever befalls you, walk on untouched, unattached.” Buddha
Source: The Dhammapada

A man has a faith. If he says, “this is my faith,” he maintains the truth. However, by that he cannot proceed to the absolute conclusion: “this alone is the Truth, and everything else is False.”

The ideas produced here are a man’s faith. Thinking about them and applying them to one’s life, one may find the Truth and happiness.
In order to be happy in life one must understand the four noble truths:

(1) Sorrow (Dukkha)
(2) Origin of sorrow
(3) Freedom from sorrow
(4) The path to the freedom from sorrow

Performance of Four Functions:

With regard to the four noble Truths, we have four functions to perform.

The first noble truth is Dukkha (sorrow), the nature of life is suffering, its sorrows and joys, its imperfections and unsatisfactoriness, its impermanence and instability. With regard to this, our function is to understand sorrow as a fact, clearly and completely.

The second noble Truth is the origin of Dukkha, which is desire, thirst, accompanied by all other passions, defilements, and impurities. A mere understanding of this fact is not sufficient. Here our function is to discard, eliminate, destroy, and eradicate desire, thirst, and passions.

The third noble Truth is the cessation of Dukkha. Nirvana is the absolute truth, our function here is to realize it.

The fourth noble Truth is the PATH, leading to the realization of Niravana. A mere knowledge of the PATH, however complete, will not do. In this case our function is to properly follow it.