Manifestation and the law of attraction isn't bullshit.

[Majed]

If reality is a hallucination, then whatever you consciously hallucinate becomes your reality. 

We can think of it even in this way, reality is infinite, hence infinite possibilities, if you focus your mind and pay attention to that which gives you opportunities to actualize your vision, you'll end up actualizing your vision. 

We can call it the law of focus. Whatever you focus on, you end up achieving. Your psychology, self-esteem, inner mindset,etc... are the primary factor in determining your success. 

Therefore yes, believing in yourself has always proven to work, and is a prerequisite for success.