The portion of the Torah that says "May G-d turn His face to the Jews" is read (in Hebrew) but not translated (into Aramaic, the language understood by the less educated).
This was so that the people who weren't learned would not think that G-d favors the Jewish people for free.
The Jewish people earn G-d's favor. The custom cited as the reason for the favor is the custom to bless G-d for bread even if a smaller than required amount of bread is eaten.
Tractate Megillah 25b. It is interesting to note that this custom is cited and not something more dramatic, like all the people who gave up their lives for Judaism. By doing what seems to be a little thing, a thing that might not even be noticed by another person, a person can merit that the entire Jewish nation will be favored by G-d. Also, we have such an intimate relationship with G-d, that G-d sees everything, big and small.
There is also a saying that there is no free choice except in keeping oneself healthy from minor illnesses. (v. Tosaphoth Megilla 25a). There may be a situation where it is unhealthy for the person to eat more than a small piece of bread. Nevertheless, even though it is not required, and even though the person might think to themselves, "I am deprived trying to do whatever I can to serve G-d, at least let me skip the prayers," instead they are eager to thank and praise G-d for the sustenance and blessing that they receive. Such a person, it makes sense, might be favored by the One providing for his/her sustenance.