Many have asked why is Parshas Ha'azinu a Shira. It is basically a strong: תְּבִיעָה demand on why we aren't more grateful to Hashem. הַלָה' תִּגְמְלוּ זאת? הֲלוֹא הוּא אָבִיךָ קָנֶךָ? לבו Is this how you repay Hashem for everything He's done for you, including your very existence? When a Yid sings, he is usually praising Hashem and thanking Him. שִׁיר וּשְׁבָחָה Song & praise, הַלֵל וְהוֹדָאָה Hallel and Hoda'ah (gratitude). We can suggest that the entire beautiful Parsha of Ha'azinu is a: תְּבִיעָה demand for more thankfulness. Thankfulness isn't easy, and almost every human suffers from the lack of it in some way; either consciously or subconsciously. A true Yid wants to be pressured and awakened to do more and more Hoda'ah. Chazal say that a person should thank Hashem for every single breath of air! And Dovid said: לֶךְ הֵמִיָּה תְהִלָּה תהלים סה ב to fully praise Him is impossible, so I will praise by being silent. The Kapitchnitzer Rebbe was always worried how can he thank Hashem more!
There is no greater song than a constant spurring yourself on for more Hoda'ah, and always protesting that you are not thanking enough. It actually rejuvenates you, and it gives you Simcha when you're always worried how can I thank Hashem more and more! Look what He does for us!
כְּנֶשֶׁר יָעִיר קִנּוֹ עַל גּוֹזָלָיו יְרַחֶף לב יא He treats us with tenderness etc. there is no end to His goodness. And the punishments for ungratefulness prove how important it is to always thank. In Novardok, one of the methods of working on Bitachon was: בְּדֶרֶךְ תְּבִיעָה demanding Bitachon from yourself, which is highly effective. "How can you not have Bitachon; are you normal??"
Believe it or not, this can give you loads of Simcha and Bitachon. It becomes easier when it is viewed as an obvious truth, and not a difficult mountain that needs to be worked on.
"Why don't you appreciate yourself and your great situation??" With a demanding “question mark”, you see more clearly. You wake up!