Don't mind other people's business.
99% of the business of 99% of other people has nothing to do with us whatsoever. So why do we feel the need to meddle in their lives? Giving them the freedom to live their lives gives us the freedom to live our own.

Have faith in the other 1%.
For that small fraction of other peoples lives that affect us, why not give them the benefit of the doubt? Why not teach them so that they're empowered to make good choices? Having that 1% there to help puts us at 101% power. That's a good place to build from.

Minding our own business
Our lives need a lot of attention, so why not do that more than minding everyone else? By spending all our time on our own success, we really won't have too much time left over to bother other people.

Getting others to mind their own business
Yeah, I hear you. 'But everyone butts into my business' is what EVERYONE says. Well, we can always remind them that they have their own business to attend to. They make not like it, but if they see how much farther they can get minding their own business, maybe they'll change their minds.

When in doubt, just show them this article. I really don't mind that at all.

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Exercise to try

Hold your tongue
When someone says or does something that you obviously think is wrong, try not saying anything. Become an observer instead, and let it play out by itself. If this is someone you really care about, stay close in case they're going to need your help, but otherwise, let them learn the results of their actions. You might be surprised; they may actually succeed on their own.