Not that it’s a pleasant thing, but it is a sign that we are trying to be better, and the capacity for self-improvement is a key part of what makes us human. Blaise Pascal, in his book Thoughts on Religion, put it this way:
Man is so great that his greatness appears in his knowing himself to be miserable. A tree is not conscious of misery. It is true, that to know oneself to be miserable is really to be miserable; but there is still something great in a consciousness of misery. Thus all his miseries prove his greatness. They are the miseries of a noble lord; the miseries of a king that has been dethroned…
What can this incessant craving, and this impotence of attainment mean, unless there was once a happiness belonging to man, of which only the faintest traces remain, in that void which he attempts to fill with everything within his reach?
Should the king in exile pretend he is happy there? Should he not seek his own country? His miseries are his ally; they urge him on. And so let them grow, if need be. But do not forsake the secret of life; do not despise those kingly desires.
Pascal continues by pointing out that our discontent hints that we are destined and made for something much greater than we are. Though there are plenty of people with one arm or eye, for instance, who wish they had two, there are very few (if any) people with two arms or eyes who wish they had three. Our sense of what we lack points us to what we were meant to be.
Though what we are meant to be resides in the future, we can content ourselves with the fact that we are continuing to grow, reach, and strive. As the poet Robert Browning put it, “A man’s reach must exceed his grasp, or what’s a heaven for?”