We approach this essay, with Hashem's help, with the goal of helping identify the role of bitachon (faith and trust in God) in our current situation (and, to a degree, by extension, in avodas Hashem (service of God) in general). It is self-evident that bitachon is a core, fundamental value.
...as Yirmiyahu emphasized, and pronounced '(Cursed is the man who trusts in mankind) and establishes flesh as his arm (17:5).' David, in all his praises, latched on to it 'In God, I trusted' (Tehilim 26:1); 'Yisra'el, trust in God' (Tehilim 115:9). Furthermore, Yeshayahu said 'Trust in God evermore' (Yeshayahu 26:4)" (Meshech Chochmah, Parshas Eikev).
It is also true, however, that Hashem has demarcated distinct, discrete domains in His world and in His Torah. Any facet of His Torah -- even one which is most holy, lofty and significant -- must be situated in it's rightful domain without infringing upon other domains. In that vein: a crucial principle regarding the role of bitachon is that bitachon in no way mitigates our obligations in other religious domains. If we are charged with mitzvos, then there is no room to defer our duties out of a sense of bitachon. "Throw your burden upon God (Tehilim 55:23)" -- but not your mitzvos, your obligations!
When the mitzvah of u'sh'mor nafshecha me'od devolves upon us, we are forbidden to substitute bitachon for the appropriate precautions and preventive measures. There can be no segulah, no talismanic stratagem, which would exempt us from this mitzvah, or any other. Functionally, bitachon works in tandem with, but not in any degree as a substitute for, all appropriate precautions and preventive measures.
To further drive home this critical principle, we would do well to consider a selection of my grandfather, Rav Soloveitchik's zt"l forceful, authoritative treatment of this dynamic in his essay, The Lonely Man of Faith[2]:
The conquest of disease is the sacred duty ... and he must not shirk it ... the Halakhah remained steadfast in its loyalty to scientific medicine. It has never ceased to emphasize the duty of the sick person to consult a competent physician. The statement quoted in both the Tur and Karo's Shulchan Aruch ואם מונע עצמו הרי זה שופך דמים "And if he refrains [from consulting a physician], it is as if he shed his own blood," which can be traced indirectly to a Talmudic passage, is a cornerstone of Halakhic thinking. Vide Yoma 82a, 82b, 83a; Kiddushin 82a; Rashi sub טוב; Bava Kamma 85a, Tosafot sub שניתנה; Tur Yoreh Deah 336; Bayit- Chadash sub תניא. See also Pesachim 56a, Rashi and Maimonides' Commentary.
The doctrine of faith in God's charity בטחון is not to be equated with the folly of the mystical doctrine of quietism, which in its extreme form exempts man from his duty of attending to his own needs and lets him wait in "holy" idleness and indifference for God's intervention. This kind of repose is wholly contrary to the repose which the Halakhah recommends: the one which follows human effort and remedial action. Man must first use his own skill and try to help himself as much as possible. Then, and only then, man may find repose and quietude in God and be confident that his effort and action will be crowned with success. The initiative, says the Halakhah, belongs to man; the successful realization, to God.
Certainly, "except the Lord build the house, they labor in vain that build it," but if those who labor stop building, there will be no house. The Lord wants man to undertake the task which He, in His infinite grace, completes.
In the above citation, the Rav focused specifically on medicine; his words are even more relevant to our topic at hand, the mitzvah of u'sh'mor nafshecha me'od. Even those solitary opinions (which were unequivocally rejected by normative halacha) that deemed standard medical care as optional perforce agree that the Torah's prescription of u'sh'mor nafshecha me'od, qua mitzvah, obligates us to take all necessary precautions and preventive measures in the face of prospective danger.
Rabbeinu Yonah[3], commenting on the pesukim in Mishlei (21:30-31) "There is neither wisdom nor understanding nor counsel against the Lord. A steed is prepared for a day of battle, but the victory is the Lord's[4]," writes:
Let us say, then, regarding "there is neither wisdom nor understanding nor counsel against the Lord," that neither wisdom, understanding, or counsel have the force to nullify [Divine] edicts, much as it says "except the Lord build the house, they labor in vain that build it."
When it says (Mishlei 21:22) that a wise man "brought down the stronghold in which it trusts," it means to say that victory and triumph are brought about [but not effected] through wisdom. It is similarly brought about through feats of strength and waging war...
What it means by saying "a steed is prepared for a day of battle [, but the victory is the Lord's]," is that people are obligated to watch out for themselves, to prepare steeds and weapons, for a time of war, and Hashem Yisbarach will save and pity on those whom He chooses to pity (see Shemos 33:19).
Let us both consider and comply with Rabbeinu Yonah's exhortation "that people are obligated to watch out for themselves... and Hashem Yisbarach will save and pity on those whom He chooses to pity." Would that we act accordingly!
May it be Hashem's will that our lot be with those who are saved and pitied.
[1]The following is a translation of Rav Twersky's Hebrew-language essay Bitachon U'P'Eloose The translators take responsibility for any inaccuracies/infelicities. (Talmidim)
[2]Pp. 89-90
[3] Cited by HaGaon Rav Shmuel Hominer zt"l in Mitzvas HaBitachon
[4] Translations of Mishlei are taken from Rabbi AJ Rosenberg's edition (Judaica Press)