Manifestation starts in the mind.
It's no use buying dozens of books on the law of attraction without a strong, healthy mind ready to manifest what you want.
The law of attraction works, and most books on the subject are good.
If you do 100 hours of mentalizing your desire, without a doubt you will be strongly attracting what you mentalized. But if you have 5 seconds of negative thoughts about your desire, you've lost all your mentalizing...