In a battle with Amelek, Torah recounts that the B’nai Yisrael were being defeated until Mosheh raised his hands:
“When Mosheh raised his hands — Yisrael won.
When he rested his hands — Amalek won.” 
The Talmud imparted no magical power to Mosheh’s hands. Rather, the rabbis believed that the active element was the devotion of the Israelites themselves:
“Whenever Yisrael contemplated what is above them
and surrendered their hearts to their Father in Heaven,
they made themselves victorious.” 
It’s still unclear from this mishnah what part Mosheh’s hands played in this. But it suggests that seeing Mosheh’s hands upraised brought about a change in the thinking or “kavanah” of the B’nai Yisrael who were engaged in battle.
What might that change have been?
Mosheh’s upraised hands suggests to me a position of imparting blessing, much as the kohanim raise their hands in blessing the congregation during the duchanen in the synagogue (and the Temple before that).
We might say, then, that when the B’nai Yisrael saw Mosheh’s hands upraised, they believed that they were being blessed by God and could not be defeated. They “surrendered their hearts to their Father in Heaven.” They saw themselves as unquestionably victorious. With that belief in their minds and hearts, they were able to defeat the same opponent who only moments earlier had been defeating them!
This is the essence of “affirmative prayer.”
Countless teachers of prayer, particularly within the New Thought movement, have referred to this same principle:
“Stop thinking about the difficulty, whatever it is, and think about G-d instead. This is the complete rule, and if only you will do this, the trouble, whatever it is, will disappear.” 
I’m about to quote Jesus. Not proselytizing in any way, I am, however, among those Jews who feel that there are things that we, as Jews, can learn from Jesus’ teachings, without making him an object of worship.
That being stated, I quote Jesus as saying:
“Whatever you ask for in prayer, believe that you have received it, and it will be yours.” 
Translations of this verse vary somewhat, but not excessively. The import is always the same: When we pray, we should do so believing that we have already received that for which we’re asking.
Given the record of Jesus’ successful healings and other acts of prayer, we might at least take his words as being those of someone who knew from experience what he was talking about. To me, he’s not saying “Ask me to pray or do something for you.” Rather, he’s telling us how to empower our own prayers!
We find this principle elsewhere in the New Thought writers. Ernest Holmes, for example, writing about prayer, says:
“We cannot afford to believe in imperfection for a single second. To do so is to doubt God: it is to believe in a power apart from God, to believe in another creator.” 
We find other examples of this in the writings of Joel Goldsmith (“The Infinite Way”) and Jose Silva (founder of “Silva Learning System,” aka “Silva Mind Control”).
This was the same prayer-principle that the Jewish Science authors sought to express from within Jewish tradition. Rabbi Alfred Geiger Moses, founder of the movement, wrote:
“Speak the healing word and avoid useless discussion of sickness.” 
In the midst of sickness (or some other negative appearance), what allows us to “see” health? It’s our imagination; that part of our minds that isn’t completely dependent on the senses for its information or its influence. As Rabbi Clifton Harby Levy writes:
“The imaginative power is the supreme gift of G-d. Just because it has so great potency, we must use it with good judgment, and for the best ends. It is the highly creative and constructive force in the spirit of man through which he builds, first the idea, and then its realization.” 
Rabbi Morris Lichtenstein, too, pointed to this as the essential element of effective prayer:
“In these mental prayers, there should never be formed any negative images…[one] should see always with his [or her] mental vision only the state in which he [or she] desires to be…” 
His wife Tehillah, who was also his closest student and disciple, similarly wrote:
“When we pray with the imagination, when we visualize our prayer, when we see with our mind’s eye the state in which we wish to be, we are addressing our prayer to the Divine forces within ourselves; we are invoking them into action by the visualized declaration of that which we wish to attain.” 
Nor is this limited to Jewish Science authors alone. Rabbi Abraham Joshua Heschel wrote:
“The focus of prayer is not the self. A man may spend hours meditating about himself, or be stirred by the deepest sympathy for his fellow man, and no prayer will come to pass. Prayer comes to pass in a complete turning of the heart toward G-d, toward His goodness and power. It is the momentary disregard of our personal concerns, the absence of self-centered thoughts, which constitute the art of prayer. Feeling becomes prayer in the moment in which we forget ourselves and become aware of G-d. When we analyze the consciousness of a supplicant, we discover that it is not concentrated upon his own interests, but on something beyond the self. The thought of personal need is absent, and the thought of divine grace alone is present in his mind. Thus, in beseeching Him for bread there is one instant, at least, in which our mind is directed neither to our hunger nor to food, but to His mercy. This instant is prayer.” 
“Prayer comes to pass in a complete turning of the heart to God, toward His goodness and power.” That’s exactly what the mishnah quoted above is saying about the kavanah of the embattled B’nai Yisrael when seeing Mosheh’s hands raised high.
We turn our mind to God by seeing God’s successful response to our state.
We don’t create the outcome of our prayer by will-power or other mental effort.
Instead, visualizing or affirming the desired state or condition, we allow it to be brought about by God — the Divine Presence in us.
 Shemot/Exodus 17:11
 Rosh Ha-Shanah 29a
 Fox, Emmet; The Golden Key; see:
 Mark 11:24
 Holmes, Ernest; The Science of Mind; p. 185
 Moses, Rabbi Alfred Geiger; Jewish Science: The Applied Psychology of Judaism; p. 131
 Levy, Rabbi Clifton Harby; The Jewish Life; p. 59
 Lichtenstein, Rabbi Morris; Prayer; Jewish Science and Health; © 1925, p. 51
 Lichtenstein, Tehillah; When to Pray and How to Pray; Jewish Science Interpreter, Apr., 1940; p. 4
 Heschel, Rabbi Abraham Joshua; The Quest for God; © 1954, p. 15