Self help and motivational books and speechs exist to make you feel better about yourself and your reality.
The reality will be the same, but you will feel more positive and happier about it. You will accept your reality and feel grateful for it.
Even if your realty really sucks, it will change how you see it and feel about it.
It will stop your suffering.
It's kind of a brainwashing.
What is not bad in this case.
Maybe there's no need for these kind of books if you understand that how you feel depends how you choose to feel about that situation, or that problem.