I’ve been keeping a file of favorite quotations since I was a teenager. This is one of my favorites – however, I don’t have my file with me, so the language may be slightly off.
It is from a book entitled The Grand Sophy by the late, great Georgette Heyer. Bear in mind the language is that of historical romance.

You have fallen into a state of despondency and there is not the least need. In fact, nothing could be more fatal in any situation. It encourages one to believe that there is nothing to be done, when all that is wanted is a little resolve to bring matters to a happy conclusion.