The biggest issue I see normally when it comes to manipulating our individual realities is belief. I ask you, what is belief? What is the true feeling and/or emotion felt when you believe in something? Ask yourself a question that you know for a fact you believe in, or something that can not be doubted. Interestingly enough, I feel nothing.
Not having to take the time to think about doubt while practicing whatever it is you are practicing is essential. Believe what it is that you want to accomplish as cliche as it may sound.