Here is an interesting point from the Parsha-from today's Hakhel email.
The Posuk teaches that Avrohom Avinu encamped to the west of the City of Ai and to the east of the City of Bais Kail. [Note: HaRav Chaim Kanievsky, Shlita, rules that the name of Hashem should not be mentioned when mentioning the City “Bais Kail”.] Chazal (Sanhedrin 44B) teach that Avrohom Avinu encamped in this place in order to daven for his descendants who he foresaw would have trouble with the people of Ai. The lesson Chazal draw from this is that “LeOlam Yakdim Adam Tefillah LeTzara - a person should always daven before a tzara takes place" with the hope that the tefilla will void the need for the tzara. We note that Chazal do not distinguish between 'sizes' of tzara, and that the lesson applies to tzaros of all kinds both large and small.
For example, as we are now in a “changing weather” season, one can certainly daven to Hashem that he not get a cold, strep, or any virus, infection, or other illness which r’l seems to be more prevalent during these times. Nothing is too big or too small for Hashem. We should be smart enough to recognize in advance that He is the Source of Everything, that He starts and stops, brings on and withholds, weakens, invigorates and reinvigorates, and can bring on pain, adjust it, and cure it. Our ability to sincerely daven to Hashem in advance, demonstrating our emunah and bitachon, may obviate the need for symptoms, events, and occurrences which may have been otherwise necessary, but are no longer needed!
In the bracha of Refa'einu, we should focus when we especially ask Hashem for "Hoshi'ainu VeNiva'shaiya" save us from sicknesses (one can, of course, be more specific in his personal requests) and their causes (Kuntres Avodas HaTefillah).
I remember reading from R' Shimshon Pincus zt"l how important it is to daven for things to stay the way they are before a bad thing happens. A person should always daven to remain healthy because it takes more zechusim to heal a sick person and more tefillos on your part than when you daven for the person before they even get sick. We can take this lesson for all aspects of our lives and daven for all kinds of things before the tragedy strikes chas v'shalom.
There are, of course, other tzaros to avoid besides sickness - the nuclear threats of madmen; the effects of an estimated tens of thousands of rockets around Eretz Yisroel in the hands of terrorists; issues relating to shidduchim, marriage and parent-child relationships, parnassah and money.... We know to Whom to turn--let us take the lesson of Avrohom Avinu and do what we can to help save ourselves, our people, and the world from pain and suffering, from difficulty and devastation - tefillah is the preemptive strike that Hashem is looking for!