It is well known that, as stated in Iggeres HaTeshuvah,1וְהִנֵּה יָדוּעַ מַה שֶּׁכָּתוּב בְּאִגֶּרֶת הַתְּשׁוּבָה
the higher rung of teshuvah is characterized by abundant joy.שֶׁתְּשׁוּבָה עִלָּאָה הִיא בְּשִׂמְחָה רַבָּה.
From this it is understood –וּמִזֶּה מוּבָן
and how much more so does this pertain to the teshuvah of Shabbos Teshuvah,בְּמִכָּל שֶׁכֵּן בַּנּוֹגֵעַ לְהַתְּשׁוּבָה דְּשַׁבַּת תְּשׁוּבָה,
when the higher rung of teshuvah manifest by a Jew is of the loftiest nature,שֶׁבִּתְשׁוּבָה עִלָּאָה עַצְמָהּ הִיא דַּרְגָּא נַעֲלֵית בְּיוֹתֵר,
to the extent that Havayah A-donai is considered as Elokim, a rung associated with contraction – that the teshuvah of such a day mustוְעַד שֶׁגַּם הֲוָיָ׳ אַ-דְנַי כֵּאלֹקִים יֵחָשֵׁב,
be carried out with abundant and prodigious joy.שֶׁצְּרִיכָה לִהְיוֹת בְּשִׂמְחָה רַבָּה וַעֲצוּמָה.
Since “joy breaks through barriers,”2וְכֵיוָן שֶׁשִּׂמְחָה פּוֹרֶצֶת גָּדֵר,
it follows that through the joy experienced during the Ten Days of Teshuvah,הִנֵּה עַל יְדֵי הַשִּׂמְחָה בַּעֲשֶׂרֶת יְמֵי תְּשׁוּבָה,
and on Shabbos Teshuvah in particular,וּבִפְרָט בְּשַׁבַּת תְּשׁוּבָה,
all boundaries and limitations will be broken through.פּוֹרְצִים כָּל הַמְּדִידוֹת וְהַהַגְבָּלוֹת,
And as a result, “G‑d will answer me with boundless relief.”3עָנָנִי בַּמֶּרְחָב יָ"הּ,
This Divine blessing will be drawn down and continue over the course of the entire year being manifestוְזֶה נִמְשָׁךְ עַל וּבְכָל הַשָּׁנָה,
in one’s spiritual matters,בָּעִנְיָנִים הָרוּחָנִיִּים,
i.e., that one’s Divine service of studying the Torah and observing the mitzvos will be in abundance, breaking through4 all obstacles;שֶׁהָעֲבוֹדָה בַּתּוֹרָה וּמִצְוֹת תִּהְיֶה בְּהַרְחָבָה וּבְאֹפֶן דְּוּפָרַצְתָּ,
and these generous blessings will also be elicited and drawn down into a Jew’s material concerns, in ample beneficence regarding children, long life and health, and sustenance,וְגַם בָּעִנְיָנִים הַגַּשְׁמִיִּים בְּבָנֵי חַיֵּי וּמְזוֹנֵי רְוִיחֵי,
including the ultimate and true prosperity that will be manifest at the time of the coming of our righteous Mashiach.וְעַד לְהַרְחָבָה הָאֲמִתִּית שֶׁתִּהְיֶה בְּבִיאַת מְשִׁיחַ צִדְקֵנוּ,
“It will expand… above,”5וְרָחֲבָה גו' לְמַעְלָה
interpreted by our Sages6 to mean that Jerusalem will expand in the Ultimate Future.עֲתִידָה יְרוּשָׁלַיִם לִהְיוֹת מֻרְחֶבֶת כו',
Indeed, in that future era, Jerusalem is destined to spread out over all of Eretz Yisrael,עֲתִידָה יְרוּשָׁלַיִם שֶׁתִּתְפַּשֵּׁט בְּכָל אֶרֶץ יִשְׂרָאֵל
and Eretz Yisrael is destined to expand over all lands,7וַעֲתִידָה אֶרֶץ יִשְׂרָאֵל שֶׁתִּתְפַּשֵּׁט בְּכָל הָאֲרָצוֹת,
with the coming of Mashiach.בְּבִיאַת מְשִׁיחַ צִדְקֵנוּ בְּקָרוֹב מַמָּשׁ.

Summary

The higher rung of teshuvah is characterized by abundant joy. Thus the teshuvah of Shabbos Teshuvah, when the teshuvah manifest by a Jew is of the loftiest nature, must certainly be carried out with prodigious joy.
Since “joy breaks through barriers,” it follows that such joyful teshuvah will break through all boundaries and limitations. As a result, “G‑d will answer me with boundless relief.” This Divine blessing will be drawn down and continue over the course of the entire year, being manifest in both one’s spiritual and material concerns. And it will include the ultimate and true prosperity that will be manifest at the time of the coming of Mashiach.