רַבִּי מֵאִיר אוֹמֵר: כָּל הָעוֹסֵק בַּתּוֹרָה לִשְׁמָהּ, זוֹכֶה לִדְבָרִים הַרְבֵּה, וְלֹא עוֹד אֶלָּא שֶׁכָּל הָעוֹלָם כֻּלּוֹ כְּדַאי הוּא לוֹ, נִקְרָא רֵעַ, אָהוּב, אוֹהֵב אֶת הַמָּקוֹם, אוֹהֵב אֶת הַבְּרִיּוֹת, מְשַׂמֵּחַ אֶת הַמָּקוֹם, מְשַׂמֵּחַ אֶת הַבְּרִיּוֹת, וּמַלְבַּשְׁתּוֹ עֲנָוָה וְיִרְאָה, וּמַכְשַׁרְתּוֹ לִהְיוֹת צַדִּיק חָסִיד יָשָׁר וְנֶאֱמָן, וּמְרַחַקְתּוֹ מִן הַחֵטְא, וּמְקָרַבְתּוֹ לִידֵי זְכוּת, וְנֶהֱנִין מִמֶּנּוּ עֵצָה וְתוּשִׁיָּה בִּינָה וּגְבוּרָה, שֶׁנֶּאֱמַר (משלי ח יד): "לִי עֵצָה וְתוּשִׁיָּה אֲנִי בִינָה לִי גְבוּרָה", וְנוֹתֶנֶת לוֹ מַלְכוּת וּמֶמְשָׁלָה וְחִקּוּר דִּין, וּמְגַלִּין לוֹ רָזֵי תוֹרָה, וְנַעֲשֶׂה כְּמַעְיָן הַמִּתְגַּבֵּר וּכְנָהָר שֶׁאֵינוֹ פּוֹסֵק, וְהֹוֶה צָנוּע וְאֶרֶךְ רוּחַ, וּמוֹחֵל עַל עֶלְבּוֹנוֹ, וּמְגַדַּלְתּוֹ וּמְרוֹמַמְתּוֹ עַל כָּל הַמַּעֲשִׂים:
Rabbi Meir would say: Whoever studies Torah for Torah's sake alone, merits many things; furthermore [the creation of] the entire world is worthwhile for his sake. He is called friend, beloved, lover of G‑d, lover of humanity, makes Hashem happy, humanity happy. The Torah clothes him with humility and awe; makes him fit to be righteous, pious, correct and faithful; distances him from sin and brings him close to merit. From him, people enjoy counsel and wisdom, understanding and power, as is stated (Proverbs 8:14): "Mine are counsel and wisdom, I am the essence of understanding, and mine is power." The Torah grants him sovereignty, dominion, and jurisprudence. The Torah's secrets are revealed to him, and he becomes as an ever-increasing wellspring and as an unceasing river. He becomes modest, patient and forgiving of insults. The Torah uplifts him and makes him greater than all creations.
This perek starts off by telling us how amazing Torah is. R' Meir in the first mishna says that one who learns Torah will be endowed with all sorts of marvelous attributes; That he will be cherished by all including by the Almighty. He proceeds to enumerate the excellence of Torah study and he tells us that one who studies Torah becomes suitable to being righteous, pious, virtuous, honest and trustworthy.
It is really worthwhile reading through this mishna carefully to see how wonderful it is to learn Torah. What is striking in this mishna, are two very interesting elements. Firstly, its tone is extremely positive without even a hint of negativity. Secondly, R' Meir doesn't say that one who learns Torah will be: righteous, pious, virtuous, honest and trustworthy. He simply says that such a person will become suitable to these qualities.
Many times while witnessing my Rebbi Harav Chaim Yisroel Belsky Zatzal giving berachos to children, I noticed that he would give them a bracha that they should grow up to be a talmid chochom and a tzadik, and that they should have a fun time doing so. This past summer I brought my own sons to receive a bracha from my Rebbi. He proceeded with the above bracha and added: "do you know how much fun it is to be a talmid chochom and tzadik?"
Rabbi Belsky truly felt that being a talmid chochom and a tzadik is enjoyable. He said in the name of Rav Moshe Zatzal that viewing Torah as anything but a pleasure is kefira.
The Rambam explains that those who wish to have ruach hakodesh and to have prophesy must first attain complete happiness.
Happiness is part of a Torah lifestyle. One who learns Torah properly will have a positive approach to life and will be happy. Happy people have an easy time doing what's right. Happiness facilitates doing what's right. It is thus that Torah doesn't necessarily make one honest and righteous. In fact, the passuk tells us צדיקים ילכו בו ופושעים יכשלו that the righteous will utilize Torah for the good but that wrongdoers will be corrupted by it. One could Heaven forbid warp Torah to justify the worst of acts.
Torah study will make someone happy. Being content in life will make it easier to do what's right.
In essence, this is what R' Meir is telling us if we learn Torah we will make ourselves suitable to do what's right and to be good people, because we will be happy people.