973. When answering Amein one should also think that it includes the beginning of the beracha "Blessed are you Hashem" and one is declaring "Amein, the name of Hashem should be blessed". Shulchan Aruch w/Mishnah Brurah 124:6 MB25
 
974. When answering Amein to a beracha of tefillah which includes a request from Hashem (e.g. Attah Chonen L'Adam Da'as) one should think "Amein, it is true that Hashem is the source of this blessing (e.g. of knowledge) and I entreat Hashem to fulfill this prayer (e.g. bless us with knowledge)". Shulchan Aruch w/Mishnah Brurah 124:6 MB25

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Rav Eliyahu Lopian would repeat the following amazing thought in the name of R' Simcha Zissel Broide (aka The Alter of Kelm), one of the prime students of R' Yisroel Salanter;
 
* It would be worthy for Hashem to create the entire universe and cause it to exist for 6000 years just so that one Jew would say "Boruch Hu U'voruch Shemo" one time!

 

* However, 1000 "Boruch Hu U'voruch Shemo's" is not equal to one "Amein"!

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Nevertheless, 1000 Amein's is not equal to one "Amein Yehei Shemei Rabbah"!
* Yet, 1000 "Amein Yehei Shemei Rabbah's" is not equal to one single word of Torah learned by one Jew!