The Kotzker zt'l translated the pasuk, לִי ְיוּןִּהת ֶׁשקֹד ֵיַׁנְשוְא as זיין איהר זאלט הייליג מענשליך, "Holy humans shall you be." The intention of his words is explained by the Sfas Emes zt'l (5632). He explains that Hakadosh Baruch Hu doesn't desire that a person have the kedushah of the malachim, because Hashem already has an infinite number of malachim in heaven. Hashem wants a person to be a human being, but a human being who is holy.
Reb Gad'l Eisner zt'l would tell chassanim (b'derech tzachus) that there are yungerleit who want to be holy like malachim, and the first thing that they do is that they become inhumane (מענטש אויס). This isn't the right path. Hashem wants our humanity, and within this parameter, to be holy.
A hint to this is that parashas kedoshim begins with the obligation to be holy, תהיו קדושים, and immediately following, it states כמוך לרעך ואהבת, that one should love his fellow man. You are expected to acquire kedushah, while simultaneously keeping the obligation to love and to be kind with your fellow man.
Leaving the Boundaries of Holiness
In a hesped that the Yeitav Lev zt'l gave for the Maharam Shik zt'l, he explained the pasuk (22:30) ֵיַׁנְשוְא לִי ְיוּןִּהת ֶׁשקֹד, "You shall be holy people to Me, ֶהָדּׂבַּש ָרָׂשוּב and flesh in the field, ֵלוּתֹאכ לֹא ָהֵפְרט it is treif and you shall not eat it." Chazal (Chulin 68:) explain that ֶהָדּׂבַּש ָרָׂשוּב refers to the flesh of the korbanos that were taken outside the walls of the Beis HaMikdash. This isn't kosher. The lesson is that when a person leaves the mechitzos, the holy walls and boundaries of kedushah, he is at risk of ruination. (This is also written in Nefesh Yonason הירא ה"ד וארא).
Not Alone in the World
It states in Tehilim (104:26) ֶקַחׂלְש ַָּרְתיָצ זֶה ָןלִוְיָת בּוֹ, "You created the Livyasan (large fish) to play with it." Why does the pasuk mention the לויתן in particular? Chazal (Bava Basra 74:) state that Hakadosh Baruch Hu created a male and female לויתן. But when Hashem saw that the world wouldn't exist if they multiplied and had children, Hashem killed the female and salted it for the tzaddikim in the future. The male לויתן remained alone. Hakadosh Baruch Hu tells the לויתן, "You are not alone in the world. Hakadosh Baruch Hu will be there with you, and keviyachol play with you." This is a lesson for all those who feel alone in the world due to their tzaros and the like. Know that you aren't alone. Hakadosh Baruch Hu is with you. He draws you near Him to be with Him.
