Any popular phrases that urge the hearer to help a good cause even if help seems unnecessary

What I’m hoping for is something along the lines of "better safe than sorry," but instead of urging the hearer to take possibly-unnecessary safety precautions, my context is one of shared responsibility for some communal benefit.

I’m similarly unsatisfied with "the only thing necessary for the triumph of evil is that good men do nothing," because that works by threatening a bad outcome for failure rather than offering a benefit for better-than-photo-finish success.

Also related "don’t let the perfect be the enemy of the good," which actually seems like the opposite of what I want. Like "a bird in the hand is worth two in the bush," it says that it’s worthwhile to accept gains already realized even if it means foreclosing on additional potential gains; ​I almost want to paraphrase Gretzky: "you miss 100% of the shots you don’t take."

Not satisfied with "it couldn’t hurt" (etc.) because the skeptical bargain there is merely that there is no downside to trying, and it might further imply the possibility of unexpected benefits in case of success.

What I’m looking for is something that recognizes the existence of "stretch goals" (for lack of a better phrase), and urges people to act in pursuit of those goals who might otherwise be willing to be free-riders on a simply mediocre outcome.

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For context, I’m writing a short story about a society that holds that every person — not just those in government — shares a responsibility to ensure that the community’s affairs are conducted well. If the task is balancing the town’s books, maybe more-than-baseline effort could yield some kind of windfall. If the task is the pursuit of justice, perhaps it’s the difference between cookie-cutter punishment vs some kind of personalized correction and rehab. If you’re a witness to something, you shouldn’t wait to be found and interviewed, you should step forward; and if nobody is even investigating, you should step forward to conduct the investigation yourself if that’s what it takes. Almost "the buck stops everywhere."

I imagine such a society would have lots of little phrases to remind each person of their duty, regardless of context. And I’m realizing that I don’t seem to have any such phrases.