When I was younger I used to be like "oh, that's ok, never mind, don't worry about it", wouldn't make waves. I still won't , or rarely make a scene, but I'm more like "Excuuuuuuuse Me!?!"
As others said above, less likely to put up with eejits, stupidity, stubbornness, not getting what I'm paying for.
Calmly and firmly and persistently asking for what I believe I'm entitled to.
I always did what I thought I was "supposed to" do, but a lot of that has gone by the wayside. Very freeing if a bit scary at times.