In Mishna 4 Rabbi Jeff discusses why Hillel's statement is relevant to the rest of the Mishna.  

Also in this class:  We try to understand the importance of community. Why community is key to ones personal development? and more...  

 {Text for the Mishna courtesy of Sefaria}  4. הוּא הָיָה אוֹמֵר, עֲשֵׂה רְצוֹנוֹ כִרְצוֹנְךָ, כְּדֵי שֶׁיַּעֲשֶׂה רְצוֹנְךָ כִרְצוֹנוֹ. בַּטֵּל רְצוֹנְךָ מִפְּנֵי רְצוֹנוֹ, כְּדֵי שֶׁיְּבַטֵּל רְצוֹן אֲחֵרִים מִפְּנֵי רְצוֹנֶךָ. הִלֵּל אוֹמֵר, אַל תִּפְרֹשׁ מִן הַצִּבּוּר, וְאַל תַּאֲמִין בְּעַצְמְךָ עַד יוֹם מוֹתְךָ, וְאַל תָּדִין אֶת חֲבֵרְךָ עַד שֶׁתַּגִּיעַ לִמְקוֹמוֹ, וְאַל תֹּאמַר דָּבָר שֶׁאִי אֶפְשָׁר לִשְׁמֹעַ, שֶׁסּוֹפוֹ לְהִשָּׁמַע. וְאַל תֹּאמַר לִכְשֶׁאִפָּנֶה אֶשְׁנֶה, שֶׁמָּא לֹא תִפָּנֶה:  

He used to say: do His will as though it were your will, so that He will do your will as though it were His. Set aside your will in the face of His will, so that he may set aside the will of others for the sake of your will. Hillel said: do not separate yourself from the community, Do not trust in yourself until the day of your death, Do not judge your fellow man until you have reached his place. Do not say something that cannot be understood [trusting] that in the end it will be understood. Say not: ‘when I shall have leisure I shall study;’ perhaps you will not have leisure.