Rather recently, books have appeared advocating "positive imagery," suggesting that if you imagine the scene that you wish to occur, this will make it happen. The first tendency is to dismiss this almost derisively. "I was laid off eight months ago. I have repeatedly imagined myself happily employed at a new job, but I am still unemployed." It is quite difficult to counter such observations. Magical thinking is juvenile, one says, and wishing it will happen does not bring it about.
Logically, I would go along with this observation. However, I came across an essay in the sefer Ohev Israel, by the Chassidic master, Rebbe Avraham Yehoshua Heschel of Apt. He cites Rashi's statement (Genesis 7:7) that Noah vacillated in his belief that there would indeed be a flood, and did not enter the ark until the rising waters forced him to. The Rebbe of Apt asks, "How can one say that Noah, whom the Torah describes as a perfect tzaddik, was lax in his belief in Hashem's words?"
The Rebbe explains that the word emunah, faith, is related to he word omein, which means "to raise up," as in the Book of Esther, which uses the word omein in the sentence that Mordecai reared Esther. This connotation, the Rebbe says, means that emunah can "raise" things, i.e., bring them about. Therefore, Noah did not allow himself to have a strong belief that the flood would occur, because he feared that this might actually cause the flood to materialize. Noah still held out hope that the people might do teshuvah that might avert the flood, and his intense emunah might hasten it. Thus, Rashi's comment is not an aspersion on Noah.
We have the principle that a positive middah is more powerful than a negative middah. If, as the Rebbe says, a strong belief (emunah) may result in a negative result, them certainly, a strong positive belief may bring about a desired result.
However, the belief must be genuine and complete, which may be difficult to achieve.
Rebbe Yitzhak Meir of Gur cited the Midrash, that before offering the Torah to the Jews, Hashem offered it to other peoples. The Moabites asked, "What does the Torah say?" and Hashem said, "You shall not commit adultery." The Moabites rejected the Torah because, "We are a lustful people. We cannot accept that restriction."
Hashem then offered it to the Edomites, who asked, "What does the Torah say?" and Hashem said, "You shall not commit murder." The Edomites rejected the Torah because, "Our father, Esau, was blessed ‘to live by the sword.'
Why did Hashem offer the Torah to other nations? So that they should not say, "You favored the Jews. If you had given us the Torah, we would have been the chosen people." Now Hashem can say, "I offered it to you, but you rejected it."
"But," Rebbe Yitzhak Meir asked, "how does that address the charges of the Moabites and the Edomites. They will still say, ‘You quoted us "You shall not commit adultery." and "You shall not commit murder," but to the Jews You said, "I am the Lord your G-d." Had you told us that, we would have accepted the Torah."
Rebbe Yitzhak Meir explained, "The Torah is intended to help a person overcome his physical drives. The primary physical drive of the Moabites was lust, and that of the Edomites, bloodshed. These are not the primary drives of the Jews. The Jews' primary drive is skepticism. Other nations could believe that idols, rivers and mountains were gods. Jews, on the other hand, witnessed many supernatural miracles, yet as the Torah relates and our history confirms, continued to doubt Hashem. Therefore, Hashem approached each nation with what would be the greatest challenge for them. For the Moabites it was restraint of lust, for the Edomites it was restraint of killing, and for the Israelites, it was to believe in Hashem.
Emunah is indeed a powerful force and may make things happen. However, sincere and complete emunah is difficult to achieve.