[T]here is neither happiness nor unhappiness in this world; there is only the comparison of one state with another. Only a man who has felt ultimate despair is capable of feeling ultimate bliss. It is necessary to have wished for death, Maximilien, in order to know how good it is to live.
Alexander Dumas (Edmund Dantés - The Count of Monte Cristo)
How little you know of human happiness you comfortable and benevolent people, for happiness and unhappiness are sisters and even twins that either grow up together or, as in your case, remain small together.
Nietzsche The Gay Science §270