One of the things I love about the Gemara is how realistic and human it is—how it portrays people, rabbis and laypeople alike, in all their complexity, never shying away from pointing out their foibles.
“Rav Yehuda said: One who is uncertain whether he recited shema or whether he did not recite it does not recite it again. One who is uncertain whether he recited emet veyatziv, must recite emet veyatziv again…Rabbi Elazar said: If one is in doubt whether he said shema or did not say shema, one must go back and recite the shema” (Brachot 21a). The saying of the shema is the way we accept G-d’s kingdom over the world, kabbalat ol malchut shamayim. It is not something we are meant to forget we have done, a short time—or even a long time—later. But forget we do, giving rise to much Talmudic discussion.
Not only might one forget if one has said the shema, one might not even remember what one has said while in the midst of saying the shema. “He read and made a mistake, but does not know where he made a mistake…between ketiva [uketavtam] and ketiva, he goes back to the first ketiva” (Brachot 16a). It’s early in the morning, one rushes to shul, quickly puts on his tefillin and tries to keep up with the davening. He begins saying the shema and gets to the verse uketavtam al mezuzot beitecha uvesharecha. Yet he cannot recall if this is the verse from the first paragraph of the shema or the second! The Gemara rules that he must go back to the beginning of the second paragraph of the shema. Better to say the pasuk three times by mistake than only once by mistake. Rav Yochanan adds an important caveat. If he had said lema’an yirbuu—which immediately follows the second uketavtam—he need not go back, as “he completed his routine”. While he may not recall saying both paragraphs, we can be quite certain he did—at least on autopilot.
Perhaps one can excuse the one’s forgetfulness regarding the shema. After all, the halacha allows one to say shema b’lechtecha vaderech, as one is walking on the way, i.e., engaged in other activities. But one should have no excuse when standing in prayer saying the amidah, when our focus must be such that “even if a king asks regarding his well-being or a snake is surrounding his ankles, he may not interrupt his prayers” (Brachot 30b). We may not have a good excuse, but that does not mean we do not, in practice, forget if we have davened. “Rabbi Elazar said: One who is in doubt if he prayed or if he did not pray does not return and pray. Rabbi Yochanan says, Halevai, if only, a person would pray all day” and thus, he should pray “again”.
The Gemara continues, “Rav Yehuda said in the name of Shmuel: One who was standing in prayer and remembered that he already prayed, stops his prayers even in the middle of a blessing” (Brachot 21a).
I find these ideas—and many others of a similar nature throughout masechet Brachot and beyond—comforting. I am following in a long line of tradition when my mind wanders while I am davening, and I may not even remember what I have or have not said. It is not realistic to expect one to be able to properly focus three (or four) times a day, 365 days a year. Our Sages were well aware of this, understood this, and incorporated such into their halachic rulings. We should not think that we are sinners when our mind wanders during tefillah.
Yet just because it is common and natural does not mean we should just accept this as the way it is. That is not the Jewish way.
Davening with kavanah requires metal toughness, which is no simple matter. Not simple, but not impossible. It requires hard work, like anything important in life. There is, however, a very simple action that all can do without much difficulty, and which will have great impact.
“Rabbi Yocḥanan said in the name of Rabbi Shimon ben Yoḥai: What is the meaning of that which is written: ‘But as for me, let my prayer be unto You, Lord, in a time of favour’? (Tehillim 69:14). When is a time of favour? It is at the time when the congregation is praying….The same was taught in a Braitta: Rabbi Natan says: From where do we know that the Holy One, Blessed be He, does not despise the prayer of the masses? As it is stated (Tehillim 55:20): ‘Behold, G-d does not despise the mighty’" (Brachot 7b-8a).
The prayers of a minyan are fundamentally different from those of an individual. It is not I alone who beseeches G-d, but I as a member of the Jewish nation, the “mighty” Jewish nation, which has remained faithful to G-d’s way of life despite our many travails. G-d may "despise" the prayers of the individual, sinful, arrogant and weak, but never those of the “mighty”. And there is nothing mightier than the community of Israel. As Rav Soloveitchik notes, an individual must meekly beg G-d to hear one’s prayer, whereas the community, tzibbur, may demand of G-d that He answer our prayers.
This idea is reflected in a second teaching brought by Rav Yehuda in the name of Shmuel. “He who already prayed and enters a synagogue to find a congregation in prayer, if he is able to introduce a new idea, [into his prayer], he should pray again, and if not, he should not pray again”.
After learning the ruling of Shmuel that one who is mistakenly praying for a second time must immediately stop his prayers even in the middle of a blessing, why the need to teach that if one walks into shul and people are davening, one should not join them? Surely, if one must interrupt one's davening, one should not begin davening. To this, the Gemara answers that one would have thought that “individual prayer compared to communal prayer—it is as if one has not prayed!” (Brachot 21b).
While in practice we do not quite go that far, the fact that one could even think that davening at home is of no significance vis-à-vis davening with a minyan should give one pause for thought. Individual prayer may not be meaningless, but it is in a different league, a much lower one, than tefillah b'tzibur. Shmuel does rule that if you can add a new idea that you did not pray for at home—something that should not be so difficult—one should, in fact, pray again with the congregation. Relying on individual prayer alone is something we should avoid.
I imagine that for many (mainly those who go to minyan on a regular basis), much of the above is obvious, whereas for others (mainly those who do not go to minyan on a regular basis), the above words are a bit jarring. There is little doubt that praying with a minyan is the gold standard—and not just for reasons of prayer. Yet at the same time, just as our Sages well understood that we may not remember if, how, or what we prayed, we can understand that for many, daily minyan is something that may not (yet) be possible. With a minyan or even without, there is no better way to start one’s day than by taking time to talk to G-d, reflecting on the beautiful words in our siddur. May we all manage to pay a bit more attention to them.
 The Rav Levi of Berditchev in me wants to exclaim, “How wonderful are the people of Israel! Even when they don’t know what they are saying, they say the shema”.
 I do think it is realistic to ask one to focus on five prayers, one day a year.
 This, in contradistinction to talking during davening. It is actually quite scary to read what our Sages have to say about those engaged in idle chatter in the middle of davening.
 This is over and above the fact that most people daven with increased focus when davening with a minyan.
 There is no difference in all the above between men and women. They, too, are part of the tzibbur and their prayers are also much more effective with a minyan. For technical reasons beyond the scope of this devar Torah, in order to create a minyan to say devarim shebekdusha, ten men are needed. But just like the 11th man on, women constitute an integral part of the tzibbur.