(Today marks the 3rd anniversary of my blog, which began on 1/12/11 with the post:
I thank everyone who has been reading it and brought it to almost 20,000 views from all over the world at this time. I hope my blog is fulfilling my intention of being an educational and inspirational resource to all people, and to both clergy and the general public. I look forward to continuing my efforts.)
This mishnah refers to an incident in which the B’nai Yisrael are strengthened in battle by the sight of Mosheh’s hands (arms) raised,  perhaps signifying to them that they were being blessed. When Mosheh, fatigued, lowers his arms to rest them, the B’nai Yisrael revert to losing the battle.
To negate belief in any “magical” power of Mosheh or his arms, the rabbis say in this mishnah that it’s the change in the thoughts or attention of the B’nai Yisrael themselves that makes the difference.
Likewise, the incident of the “brass serpent” —
“Mosheh made a brass serpent
and placed it on a pole;
If a serpent bit a man
and he looked at the brass serpent,
he lived.” 
about which the rabbis similarly said:
“In the moment when Yisrael contemplated what is above them,
and surrendered their hearts to their Father in Heaven,
they healed themselves.” 
This is how Affirmative Prayer works, too.
First: What is “Affirmative Prayer?”
Ordinarily, when we pray to ask G-d (or “the universe,” etc.) for some specific outcome, we likely phrase it as a request: “Please give me…” The underlying thought — and statement — is that we don’t have what we want now.
In “Affirmative Prayer,” we state our request as having already occurred: “I am happy;” “G-d is filling me with happiness;” etc.
Does “Affirmative Prayer” work as promised?
The quantitative data (e.g. scientific studies) is somewhat mixed. There are so many variables that it’s almost impossible to measure the results of Affirmative Prayer categorically; only that it produces certain effects under certain conditions.
In one very interesting study, for example, people with low self-esteem actually worsened when given a positive affirmation to repeat! This seems to be because the affirmation (positive “self-statement”) contradicted what the person perceived to be true about him/herself.  Still, we should notice that the affirmation did have an effect; just not the one we initially sought. As with any tool, its use is subject to the context in which it’s being used.
The qualitative data (e.g. personal or traditional anecdotes) is much more positive, but less strictly reliable. Still, it’s rather consistent and overwhelming in quantity, over a wide range of eras and places. The above stories from Torah are themselves part of the immense body of qualitative data. Some time ago, I wrote about another example, in which a Habad Hasidic Rebbe tells one of his hasidim: “Think well and it will be well.” 
The Torah-view, as understood in the Talmud, seems to say that Affirmative Prayer works! Mosheh’s uplifted arms could themselves be understood as an affirmative statement to the B’nai Yisrael. So could the brass serpent.
The mishnah makes a deep point: When, by his upraised arms, or a brass serpent, Mosheh caused the B’nai Yisrael to contemplate [מסתכלין] what is “above” — [מעלה] i.e. that which transcends and overrides all presenting conditions — they were strengthened and invigorated, ultimately to the point of victory and healing that could not be otherwise expected.
If we carry this over to Affirmative Prayer, we can say:
When we believe — or are at least willing to do so — that G-d can override any presenting condition, and is willing to do so, we have taken our attention and placed it “above.”
When we allow G-d to be expressed in our lives as our perfect Good — or are at least willing to do so — we have “surrendered our hearts to our Father in Heaven.”
If, when we make our positive statements, we do so deeply contemplating that we are making them to the ultimate Source of all, Which — or Who — can override all apparent conditions, and Which — or Who — responds in kind to our words, we will strengthen our prayers, and ourselves, immeasurably.
 Shemot/Exodus 17:11
 Rosh Hashanah 29a
 Bamidbar/Numbers 21:9
 Rosh Hashanah 29a
 http://www.psychologytoday.com/blog/wired-success/201305/do-self-affirmations-work-revisit https://rabbielimallon.wordpress.com/2011/01/16/hasidut-and-positive-words/