This works in any form of categorical subject, that whatever you convince your mind to believe will occur. This is why Christians were specifically commanded to change their thinking and realize that the way that they thinking is not of God but of the world.
Remember that we were born in sin and shape in iniquity. In other words, our minds would have been lost and have no way of focusing on anything that is correct or according to the word of God. But then Jesus came and provides the Spirit of a sound mind, which enables us to rely and stand firm on what God said through His word.
For God hath not given us the spirit of fear; but of power, and of love, and of a sound mind. 2 Timothy 1:7 (KJV)
However, God cannot give what He doesn't have; He also had a sound mind. (Numbers 23:19) God is not a man, that he should lie, nor a son of man, that He should change His mind. Does He speak and then not act? Does He promise and not fulfill?
This is how you are able to "Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you" Matthew 7:7 (KJV)
Now, when you go before God, asking Him to performing a miracle on your behalf, if you intended for you prayer to manifest, ensure that you have a sound and well made up mind.
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Motivational Speaker/author Carl feature his new book - "LIFE IS WHAT YOU MAKE IT - Seven steps to moving forward.