To be unhappy while God's will is being served and to be happy while one's own desire is being served are not the distinction of a devotee. Persons are always attracted towards new things. One is bored by having everyday the same kind of food or dress and feels pleasure in the things that are daily changing. As such if we see that we find attraction in changeable things, we should then understand that we are not eager for God. There is no happiness in changeable things.
Happiness lies in permanency.
We desire to have permanent or eternal happiness but we search for it in changeable things and for that reason we wish to keep hold on such things. Imagination of happiness in such things is the cause of unhappiness since their separation is certain. When we remain unperturbed in adversity, our mind works correctly in finding a suitable way to get out of the adversity. Whatever we speak in a fit of anger are not worth hearing or taking note of and similarly whatever we speak while we are perturbed are not worth relying words or sentences, simply because our mind in those moments is not sound or steady. In such a vast world our attachment is with limited place, time and thing.