It is not only the act of doing something, through which one could merit Divine assistance, but even the intention of doing a Mitzvah could bring spiritual protection upon a person. Rav Chaim Volozhiner zt"l writes: הִנֵּה יָדוּעַ כִּי בְּעֵת יַעֲלֶה עַל רַעְיוֹנֵי אִישׁ לַעֲשׂוֹת מִצְוָה נַעֲשָׂה רְשׁוּמוֹ לְמַעְלָה וּמִתְעוֹרֵר עָלָיו אוֹר מַקִּיף מֵהַקְּדֻשָׁה וְסוֹכֵךְ בְּאֶבְרָתוֹ... וְהוּא לוֹ לְעֵזֶר וּלְסַעַד לִגְמֹר הַמִּצְוָה - Behold, it is known that when the desire to perform a mitzvah enters one's mind, it leaves an impression On High, and the person wishing to do the Mitzvah is enveloped in a great spiritual light that shelters over him which, in turn, assists the person to actually perform the Mitzvah... for, [by merely the intention, the person is considered to be] sitting in a holy, prominent place in Gan Eden. (רוח חיים ריש אבות ד"ה כל ישראל)
These words clearly imply the great value of one's intention of performing a Mitzvah, before actually executing it; it already creates a spiritual impact.
The Kli Yakar emphasizes another important aspect of this lesson. Not only will the initial effort generate the Devine assistance in finishing the task, it is precisely this action that a person will be accredited for.
We find in סֵפֶר דְּבָרִים that Moshe Rabeinu was repeatedly encouraging and hastening Klal Yisrael that they should keep the Torah. One example is the pasuk in Parshas Va'eschanan where he urged them וְשָׁמַרְתָּ אֶת חֻקָּיו וְאֶת מִצְוֹתָיו אֲשֶׁר אָנֹכִי מְצַוְּךָ הַיּוֹם אֲשֶׁר יִיטַב לְךָ וּלְבָנֶיךָ אַחֲרֶיךָ - You shall observe His decrees and His commandments that I command you today, so that He will do good to you and to your children.
In the very next pasuk, the Torah tells us that מֹשֶׁה רַבֵּנוּ assigned three cities in עֵבֶר הַיַּרְדֵּן, where the Yidden were at that time, to serve as Arei Miklat. As the pasuk states: אָז יַבְדִּיל מֹשֶׁה שָׁלֹשׁ עָרִים בְּעֵבֶר הַיַּרְדֵּן... לָנוּס שָׁמָּה רוֹצֵחַ. Then Moshe set aside three cities on the bank of the Jordan [river]. The meforshim point out that since these two pessukim immediately follow one another, there is some connection between them, though, on the surface, they seem to be totally unrelated. The Kli Yakar helps us understand this as follows:
Dovids Part in Building the Beis Hamikdash
We know that Dovid Hamelech was not the one to build the Beis Hamikdash; Hashem explicitly told him הֱטִיבוֹתָ כִּי הָיָה עִם לְבָבֶךָ רַק אַתָּה לֹא תִבְנֶה הַבַּיִת כִּי אִם בְּנְךָ... הוּא יִבְנֶה הַבַּיִת לִשְׁמִי You have done well by having this in your heart. You, however, shall not build the Temple. Rather your son... he will build the Temple for My Name. (מלכים א', ח' י"ט)
Nevertheless, Dovid bought the plot of land where the Beis Hamikdash was to be built (see דברי הימים א', כ"א, כ"ב). Additionally, he informed his son Shlomo Hamelech that he had gathered the materials needed for building; וְהִנֵּה בְעָנְיִי הֲכִינוֹתִי לְבֵית ה' זָהָב כִּכָּרִים מֵאָה אֶלֶף וְכֶסֶף אֶלֶף אֲלָפִים כִּכָּרִים וְלַנְּחֹשֶׁת וְלַבַּרְזֶל אֵין מִשְׁקָל כִּי לָרֹב הָיָה וְעֵצִים וַאֲבָנִים הֲכִינוֹתִי, I have prepared for the Temple of Hashem a hundred thousand talents of gold, a million talents of silver, and an amount of copper and iron which is not weighed because of its abundance, and I have prepared timber and stones (דברי הימים א, כ"ב, י"ח).
Though Dovid knew that he would not build the Beis Hamikdash, nor would it be built in his lifetime, he still invested as much effort and resources he was able to, in preparation for it.
In fact, he was so dedicated to this lofty task, that the Beis Hamikdash is called in his name. Chazal comment on an apparent contradiction between two passukim. One passuk says שִׁיר הַמַּעֲלוֹת לִשְׁלֹמֹה אִם ה' לֹא יִבְנֶה בַיִת שָׁוְא עָמְלוּ בוֹנָיו בּוֹ - a song at the steps, of Shlomo Hamelech. If Hashem will not build a house [the Beis Hamikdash] its builders have toiled in vain (תהלים קכ"ז א'-ב'). It seems from here that Shlom Hamelech built the Beis Hamikdash. The second passuk says מִזְמוֹר שִׁיר חֲנֻכַּת הַבַּיִת לְדָוִד - a song of praise in honour of the inauguration of the House [the Beis Hamikdash], composed by Dovid Hamelech (תהלים ל' א'). This, on the other hand, seems to imply that Dovid built it, which was not actually the case.
Chazal explain, it was indeed Shlomo Hamelech who actually built and inaugurated the Beis Hamikdash, as is indicated by the fact that the passuk uses his name in this regard. Nevertheless, since Dovid Hamelech invested such great effort in founding it, the passuk uses his name in relation to its actual dedication (פסיקתא זוטרתא לקח טוב, שיר השירים א).
Similarly, there were forty-eight עָרֵי מִקְלָט in Eretz Yisrael. Six of these were aligned - there were three in עֵבֶר הַיַּרְדֵּן which were directly opposite Eretz Yisrael. The three in עֵבֶר הַיַּרְדֵּן only operated once the three in Eretz Yisrael were designated. As such, one might have thought that there would be no point in preparing the three in עֵבֶר הַיַּרְדֵּן before the three in Eretz Yisrael were standing. Yet, Chazal tell us, Moshe Rabeinu devoted much time during his final months preparing the Arei Miklat in עֵבֶר הַיַּרְדֵּן, although they would only be effective after the Yidden enter Eretz Yisrael, after Moshe's passing. Thus, all his hard work may seem in vain. Still, Moshe Rabeinu saw it necessary to set them up since 'מִצְוָה שֶׁבָּא לְיָדִי אֲקַיְּמֶנָּה', 'let me do my part in this Mitzvah, although it may not seem 'sufficient' (מכות דף י.).
Based on this idea, the כְּלִי יָקָר explains the flow of the passukim quoted above: וְשָׁמַרְתָּ אֶת חֻקָּיו וְאֶת מִצְוֹתָיו אֲשֶׁר אָנֹכִי מְצַוְּךָ הַיּוֹם, meaning that if one has the opportunity to perform a Mitzvah, he shall do so immediately, even though it will only be completed at a later point in time and thus he will not see it through to the end. More so, even if the Mitzvah will only be completed after one's lifetime, he should still do all he can now.
The passuk then continues אָז יַבְדִּיל מֹשֶׁה שָׁלֹשׁ עָרִים בְּעֵבֶר הַיַּרְדֵּן. After imparting this message to כְּלָל יִשְׂרָאֵל, Moshe Rabeinu immediately implemented this idea by designating three sites which will eventually serve as Arei Miklat. Because, despite knowing full well that these עָרֵי מִקְלָט would be ineffective on their own until the other three in Eretz Yisrael were set up, Moshe Rabeinu wished to do his part in building them, thus setting a real-life example of the idea he had just preached to the Yidden (כלי יקר דברים ד' מ"א).