Be careful what you wish for, you just might get it. (Potter, 2009)The wish is father to the thought.
"Our beliefs and expectations are influenced by what we want or hope to be true." Source for meaning: Martin H. Manser (2007). The Facts on File Dictionary of Proverbs. Infobase Publishing. p. 304. < Mieder, Wolfgang; Kingsbury, Stewart A.; Harder, Kelsie B. (1992). A Dictionary of American proverbs. pp. 710. , p. 303