Q. The Gemora tells us that we should daven that we should not get sick rather than daven for a recovery after getting sick, because one needs more merits to recover.
Where in Shemoneh Esrei do we daven that we should not get sick?
A. Talmud (Shabbos 32a) teaches that one should always pray for mercy not to become ill, since once he does, he requires merits to be healed. Tosafos (Rosh Hashana 16a, d’h K’maan) quotes in the name of Rabenu Tam that only according to Rav Yosi that a person is judged daily, one should pray not to become ill.
Mishna Berura (119: 1) rules on adding one’s own personal tefilos and requests, when one prays for the future, not to become ill, he should do it on the bracha of Shomea Tefilah, and not on Refaenu, which is dedicated to the ones already in distress. (Shevet Halevi 8: 21, presents a conflicting opinion)
We do find set prayers for not becoming ill in the future, in the brocho of Hamapil, (before falling asleep), on the viduy of Yom Kippur, and on Tashlich.
Horav Chaim Kanievsky Shlit’a (Sh’ma’s Tefilosi p. 135) explains why there is no set tefilah for not ailing in the future, since it is included in the last brocho of the amidah: “Sim Shalom Tova Uvracha”
Minchas Aviv (Shoftim, p. 382) points out that the eminence and distinction of the many medical books written by the Rambam, was not only in healing, but mainly in preventing illnesses and keeping people healthy. This he clearly expresses in the beginning of the second chapter of H, Deois and in the Shemono Perokim (3).
Horav Aharon Miller Shlit’a mentioned that his father answered similar to what Horav Chaim Kanievsky Shlit’a replied.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit”a