I completely agree in the power of a simple "No, Thank you." As a mother to a 16 year old I know these kids live in different times than I did and knew at the same time some things stay the same - and how important having boundaries is (as a kid and even now) and that its ok to say NO, and you dont have to give a reason either.

I feel like the more people who practice this the more society will eventually accept the "NO." I find some people arent accustomed to hearing it and they want justification as to why lol

No is no, for many of my reasons none of which I care to share.