Personal prayers-Praying in distress:
A. The Mitzvah:
[According to all Poskim] it is a Biblical command to Daven to Hashem in a time of need, when one is in a state of distress and requires Divine assistance. [Furthermore, this is the main intent of prayer, to pray for one’s needs and desires to be fulfilled. Hence those personal prayers which request from Hashem his personal needs carry a special quality that is not found in the set daily prayers. Accordingly, each time one Davens Shacharis, Mincha and Maariv and feels distressed over the exile, he fulfills the Biblical command of prayer according to all. Personal prayers may be said any time he desires and it is not necessary to recite them only in Shemoneh Esrei.]
B. How to pray the personal prayers:
Is one to verbalize the words, or may they only be said in his thought? The words are must be verbalized and not just said in one’s thought.
Aloud versus quietly: Some Poskim rule that personal prayers carry the same laws and guidelines as does Shemoneh Esrei in terms of the prohibition against raising one’s voice, and one is hence to say his personal prayers in silence. Intending towards Jerusalem: Some write that when saying personal prayers one is to intend that his prayers are elevated through Jerusalem and the site of the Temple.
Saying Hashem’s name: One may mention Hashem’s name in his personal prayers, and is to preface it with the words “Yehi Ratzon Milifanecha..”.
C. In what language are the personal requests to be said in?
One is to be particular to say his requests in Lashon Hakodesh if he [is fluent in the language and] understands what he is saying. If, however, he does not understand Lashon Hakodesh, he is to say his requests in whatever language he understands. [Furthermore, if he can express himself better in his native language than in Lashon Hakodesh he is to do so, as the main thing is that the prayer should come from the bottom of one’s heart. Accordingly, many are accustomed to recite their requests in Yiddish or other native language, even if they know Lashon Hakodesh. Also, to note, the Hebrew language spoken in Israel today, while similar to Lashon Hakodesh, is not considered Lashon Hakodesh in this regard unless one divests from it the foreign words that were introduced to the language. Thus, modern Hebrew is not preferred over one’s native language for making personal requests, unless one can divest his words from the modern Hebrew words.]
When Davening with a Minyan: Whenever one is Davening with a Minyan he may say his requests in whatever language he understands, even if he also understands Lashon Hakodesh. [Some say that this applies any time ten people are gathered together, even if they are not in the midst of prayer. Nevertheless, it is best in all cases to say one’s personal prayers in Lashon Hakodesh even when one is with the congregation, if he is fluent in the language.]
When Davening in front of the sick: When praying and asking for mercy in the presence of the sick person then one may do so in any language he desires [even if he also understands Lashon Hakodesh]. When, however, one is not in his presence, he is to only ask in Lashon Hakodesh.
D. Praying on behalf of another:
One who is praying and arousing mercy on behalf of another, needs to mention that person’s name in the prayer, if he is not making the request in front of the person. [Even one who is praying for his father is to mention his father’s name rather than simply say my father. Other Poskim however rule one may say my father, although he is not to mention any title prefix [i.e. honorifics] to his name, such as “my master or teacher” and the like, as there is no prestige before G-d.]
E. Davening for healthy children that follow the path of Torah:
It is proper for one to Daven daily on behalf of his livelihood and that the words of Torah do not cede from his mouth or the mouth of his children and that all of his descendants be true servants of Hashem.
 M”A 106/2 in name of Semak “It is a Mitzvah to Daven in a time of need”; Ramban Sefer Hamitzvos Hasagos on Mitzvah 5 “However perhaps the intent of the verse “And to serve Him” is to teach us that one is to call onto Hashem in a time of suffering and that our eyes be lifted to Him like the eyes of a slave to his master…” [See Chinuch ibid who writes the Ramban is unsure as to if this is the meaning of the Mitzvah; Likewise see Chinuch ibid who learns Ramban to refer even to a private Tzarah, and not just Tzaras Hatzibur; See Igros Moshe 2/25] Chinuch Mitzvah 433 in explanation of Shoresh HaMitzvah “Hashem commanded us to pray in order so we always ask Him for our needs and desires. Aside for receiving our requests we also penetrate our hearts with faith in Hashem and that he oversees everything”; Derech Mitzvosecha ibid
 Likkutei Sichos 29/183; Piskeiy Teshuvos 89/1; Vetzaruch Iyun if this means that according to both Ramban and Ramban this is a Biblical command, or if it means that even according to Ramban it is a Biblical command when in need. The practical ramification is in a case that one already Davened that day, do we say that Davening again in a time of need is a Biblical command even according to Rambam, or only according to Ramban.
 Likkutei Sichos 29/183 “The main aspect of prayer is to effect a change, and such an aspect is not so relevant to the daily prayers but rather specifically in the personal prayers where one requests a real and true salvation from his current state. This is why the Ramban and others argued on the Rambam and held that the command of prayer is not daily, but rather when in need.”
 See Imrei Pinchas 62; Kol Mivbaser; Magen Avraham Balak in name of Besht; Machaneh Yisrael [of Chofetz Chaim] 10; Hamagid Taluma Brachos 30b; Igros Chazon Ish 23; Piskeiy Teshuvos 89 footnote 19
 Divrei Yoel 139
 Hamagid Taluma Brachos 30b; Igros Chazon Ish 23;
 Admur 62/3 regarding Shema; 185/2 regarding Birchas Hamazon; 206/5; Admur Hilchos Talmud Torah 2/12 “All speech dependent Mitzvos one does not fulfill his obligation with mere thought”; Tanya chapter 38; Shaareiy Teshuvah 116/1; Kaf Hachaim 119/1
 Machazik Bracha end of 101, brought in Shaareiy Teshuvah 101/6
 The reason: This is learned from the prayer of Chanah, which was a private prayer, and nevertheless serves as the source for this prohibition. So is also implied from the wording of the Gemara Brachos. [ibid]
 Machaneh Yisrael of Chofetz Chaim end of chapter 10
 Igros Chazon Ish 23
 Admur 101/5
 1st opinion/explanation in Admur 101/5 and Michaber 101/4 that by personal requests for an ill person or another family problem one is to be particular to say it in Lashon Hakodesh, and only set prayers may be said in other languages; Rif Brachos 2/7; Rabbanei Tzarfat; Yearos Devash Derush 1; Chayeh Adam 24/19; M”B 122/8; Shulchan Hatahor 118 footnote 5 all conclude like this opinions
The reason: One is to always say personal requests in Lashon Hakodesh as the angels [Malachei Hashareis] don’t understand other languages, [1st explanation in Admur ibid; Taz 101/4 and M”A 101/6] and a private prayer needs the angels to elevate and vouch for his prayer’s acceptance. [Admur ibid; Rif Brachos 2/7]
Other opinions in Admur: Some Poskim rule that the angels understand all languages, even thoughts, other than Aramaic, and therefore one may Daven [even personal prayers-Michaber ibid] in any language he desires except for Aramaic. [2nd explanation in Admur ibid; 2nd opinion in Michaber 101/4 as explained in Taz 101/5 and M”A 101/7; Rosh Brachos 2/2; Tosafus Shabbos 12b, brought in Taz ibid]
 Admur ibid; M”A 101/5 in name of Asara Mamaros Mamar Eim Kol Chaiy 1/31 and Sefer Chassidim 588 and 788; Chayeh Adama and M”B ibid
The reason: As a prayer without intent is worthless. [Admur ibid]
 See Chayeh Adam and M”B ibid; Beis Baruch 22/6; Piskeiy Teshuvos 101/7; This follows the second opinion mentioned in
 See Igros Kodesh of Rebbe Rayatz who states that today, after all the innovations of words in modern Hebrew, it is no longer considered Lashon Hakodesh and hence the reasons behind avoiding speaking mundane speech in Hebrew [See Igros Kodesh Rebbe Rashab 2/459] is no longer applicable; Taharas Yom Tov 8/120
 See Piskeiy Teshuvos 101 footnote 58
 Admur ibid; Michaber 101/4; Mishneh Sotah 32a
Other opinions: Some Poskim rule one may only Daven in another language if there are 10 people Davening in that language. If however the Minyan is Davening in Lashon Hakodesh then an individual may not Daven in another language. [Yifei Laleiv 101/10; Kaf Hachaim 101/18] It is clear from the wording of Admur and Poskim ibid unlike this approach, and so writes Piskeiy Teshuvos 101 footnote 41, and so rules Chasam Sofer O.C. 84 and on Shabbos 12b and Makor Chaim 101/4
 The reason: As when Davening together with the congregation one does not need angels to elevate and vouch for one’s prayers as the verse states “Hein Kel Kabir Lo Yimas.” [Admur ibid; Taz 101/4] Meaning, that Hashem Himself accepts their prayer, without the medium of an angel. [M”A 101/6]
 Piskeiy Teshuvos 101/7
 Yearos Devash Derush 1; See Chayeh Adam 24/19; M”B 122/8; M”B 101/13; Biur Halacha ibid “Yachol Lihispalel”; Piskeiy Teshuvos 101 footnote 57
The reason: As Lashon Hakodesh has many Segulos, and with it the world was created. The words themselves help effect the blessing. [Biur Halacha ibid; See Igros Kodesh Rebbe Rashab 2/459]
 Michaber Y.D. 335/5; M”B 101/16; Shabbos 12b
 The reason: As the Shechina is found by the ill person. [ibid]
 The reason: As the Shechina is present near the ill person and when one requests mercy it reaches straight to Hashem. However, when not in his presence, one needs the assistance of the angels to elevate the request and hence should ask for it in Lashon Hakodesh as the angels don’t understand every language. [Shach 335/3; Taz 335/3; Shabbos ibid] Now, although it is disputed in Rishonim as to whether the angels understand the other languages, and some [Rosh, brought in Admur 101/5] hold they understand all languages other than Aramaic and others [Rif, brought in Admur 101/5] hold they only understand Lashon Hakodesh, nevertheless, by an ill person one is to follow like all opinions being he is in need of mercy and hence pray only in Lashon Hakodesh. [Taz 335/5; Perisha 335, brought in Nekudos Hakesef; Admur 101/5]
 Admur 119/3; M”A 119/1; See Brachos 34a
 Kneses Hagedola Y.D. 240 in name of Sefer Chassidim; Rav Akiva Eiger; Kaf Hachaim 119/6
 Maavor Yabok Mamar Sifsei Tzedek 8, brought in Chida Shiyurei Bracha Y.D. 335
 Chayeh Adam 24/19; M”B 122/8