“Positive thinking... allows you to create rational coping self-statements and images that aid your goals and enhance your life. However, it is limited, and sometimes even dangerous, b/c you can easily use it unrealistically and polyannaishly. Thus, you can positively tell yourself, “I can accomplish anything I want!” But, of course you can’t. You can enthusiastically think, “Everything will happen for the best.” But, alas, it won’t. Positive thinking, moreover, often covers up and doesn’t really remove your underlying negative thinking.”
Albert Ellis & Robert A. Harper