I loved this quote from a New York Times opinion piece by Oliver Burkeman, who has a book coming out entitled “The Antidote: Happiness for People Who Can’t Stand Positive Thinking.”
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.
I have always preferred a healthy sense of realism (and even a little self-flagellation) over any power of positive thinking.