And the way I see it the only way around it is cultural indoctrination.
It doesn't have to be a negative concept. It can be as simple as picking up a can as you walk by it on the street, and otherwise having a completely normal life. People with you can then see "huh, I can contribute just a little bit, feel good about it, without going full hippie high-viz jacket and tongs with a trash bag every weekend."
Yes. Small things help. Or at least not making it worse. One doesn't have to be a Greenpeace activist to not throw trash on the street, normal everyday behavior would be enough in this case. If only all other societal problems were so easy to solve!
It doesn't have to be a negative concept. It can be as simple as picking up a can as you walk by it on the street, and otherwise having a completely normal life. People with you can then see "huh, I can contribute just a little bit, feel good about it, without going full hippie high-viz jacket and tongs with a trash bag every weekend."