The final chapter in Oliver Burkeman's marvelous book, "The Antidote: Happiness for People Who Can't Stand Positive Thinking," is called Negative Capability. I liked it a lot.
Get your negative on! You'll feel better. Here's some excerpts from the chapter.
That letter [by the poet John Keats] records what one Keats biographer has called a 'touchstone moment' in the history of literature:
I had not a dispute but a disquisition, with Dilke on various subjects; several things dove-tailed in my mind, and at once it struck me what quality went to form a Man of Achievement, especially in Literature, and which Shakespeare possessed so enormously: I mean Negative Capability, that is, when a man is capable of being in uncertainties, mysteries, doubts, without any irritable reaching after fact and reason...
...Sometimes the most valuable of all talents is to be able not to seek resolution; to notice the craving for completeness or certainty or comfort, and not to feel compelled to follow where it leads.
...The point here is not that negative capability is always superior to the positive kind. Optimism is wonderful; goals can sometimes be useful; even positive thinking and positive visualisation have their benefits.
The problem is that we have developed the habit of chronically overvaluing positivity and the skills of 'doing' in how we think about happiness, and that we chronically undervalue negativity and the 'not-doing' skills, such as resting in uncertainty or getting friendly toward failure.
...You might choose, of course, to dedicate your life to Stoicism, like Keith Seddon in his wizard's cottage in Watford; you might undergo a completely life-transforming experience in the manner of Eckhart Tolle.
But you can also treat these ideas as a toolkit, from which tools can be borrowed as necesssary. Anyone can become somewhat Stoic, or a bit more Buddhist, or practise memento mori a little more frequently; unlike far too many self-help schemes, which purport to be comprehensive guides to life, the negative path to happiness isn't an all-or-nothing affair.
...Ultimately, what defines the 'cult of optimism' and the culture of positive thinking -- even in its most mystically tinged, New Age forms -- is that it abhors a mystery. It seeks to make things certain, to make happiness permanent and final.
And yet this kind of happiness -- even if you do manage to achieve it -- is shallow and unsatisfying. The greatest benefit of negative capability -- the true power of negative thinking -- is that it lets the mystery back in.
...The real revelation of the 'negative path' was not so much the path as the destination. Embracing negativity as a technique, in the end, really makes sense only if the happiness you're aiming for is one that can accomodate negative as well as positive emotions.
...The negative path to happiness, then, is a different kind of path. But it is also a path to a different kind of destination. Or maybe it makes more sense to say that the path is the destination? These things are extraordinarily hard to put into words, and the spirit of negative capability surely dictates that we do not struggle too hard to do so.
'A good traveler has no fixed plans,' says the Chinese sage Lao Tzu, 'and is not intent upon arriving.' There could be no better way to make the journey.