“The relentless cheer of positive thinking begins to seem less like an expression of joy and more like a stressful effort to stamp out any trace of negativity. A positive thinker can never relax, lest an awareness of sadness or failure creep in. And telling yourself that everything must work out is poor preparation for those times when they don’t. You can try, if you insist, to follow the famous self-help advice to eliminate the word ‘failure’ from your vocabulary — but then you’ll just have an inadequate vocabulary when failure strikes.”