Changing the destructive things you say to yourself when you experience the setbacks that life deals all of us is the central skill of optimism.

You must not think that what is hard for you to master is humanly impossible； and if it is humanly possible， consider it to be within your reach.

Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence.