IMHO dont be afraid to take it with a grain of salt. don't expect to be rewarded for saying no. don't expect a light feather ruffling. don't expect light consequences. be prepared to get fired. be prepared to get demoted. be prepared to lose your health insurance. be prepared to change your industry. be prepared for the realities that most people face.
if you say no to something that really is important, then there will, the vast majority of the time, be major consequences. dont expect it to be easy. dont expect a reward. dont expect anyone to even understand or care why you are doing it. dont expect to be respected. dont expect anything. be prepared.
when you are living in poverty or are homeless, that no wont really mean much. only say no when you have the ground to stand on that can catch you when the inevitable smack in the face comes.
and dont feel ashamed if you have to say yes to survive once in a while. its actually what most people do. every day. even people you respect as heroes. sometimes especially the people you respect as heroes. when a really big no comes, there will be many people chanting it together, and many others behind them silently backing them up, all of whom had to say yes, in ways large and small, at some time or another, in the past, just to survive long enough to be together in that space, building that critical mass, and supporting each other.