All of us want to be happy. Yet our joys are short-lived.
Here's what Swami Rama said about this:
In the external world there is no object that can make you happy, because all objects are subject to change, death, decay, and decomposition. That which is subject to change, and is not everlasting, can never give you happiness. It can give you only momentary joy.
That momentary joy is evidence enough that there is something that is called joy. You are searching in the wrong place. If you receive everlasting joy, and if you have attained everlasting joy, then you'll be free. It is for that freedom and for that great joy that you live. (Sadhana: The Essence of Spiritual Life, Pp. 81-82.)
What is the right place to search for this everlasting joy? Not in this world of objects.
Rather, that joy is waiting to be discovered within. Joy is the nature of our True Self. The purpose of Yoga, of meditation, is to realize that Self.