Ever seen the movie Yes man or read the book?

The core values are great, potentially addictive, but they're not long term. It's true, that positivity breeds positivity and negativity does the same to itself. Perhaps in the face of adversity, when all is to shit and every options is just as shit, that positivity can lead you to a wild card, unexpected moment. Maybe that's where the philosophy of this thinking is situated.

But

Realism helps, but it can also be the door to "negativity".

I think life is about a healthy balance of the two...