もったいない (勿体無い)(勿体ない) can mean "what a waste!" / "too good". Apparently it is originally (?) a buddhist term meaning “The essence or quality of the thing does not exist,” and supposedly has been popularized in recent years by environmentalists. I saw it used in this context:

24時間365日、どこにいてもこれからは、もうずーっと素直でいる。

じゃないと今日の興味にも失敗にも向き合えないまま。

もったいないから素直でいる！

Wherever I find myself, I want to live honestly, 24 hours a day, 365 days a year.

If not, I wouldn't be able to face the joy or failure that each day brings .

I don't want to waste time (on that) so I will stay true to myself!

My friend told me the most common usage of もったいない is when receiving a gift, as in "too good. i don't deserve it" . She says it is also used, for example, when one leaves food uneaten, to be thrown away, as in "what a waste." What is the connection of the buddhist term to both of these meanings and what is the most common use and meaning of this phrase?(I am interested most in its colloquial manifestations)

The very loose translation of this passage was mine, so any corrections of mistakes or misinterpretations is appreciated. (In particular, I don't understand how the Japanese writer is using this word here)

reference:http://www.seattlebetsuin.com/EcoSangha/glossary.htm