Suggesting people to go vegan for 1 day isn't meaningful change.
Why tell someone to be perfect for 1 day instead of being imperfect, but better for the rest of their lives?
People can make a much bigger difference if they started small like having one vegetarian meal a week. When you give small goals, people are more inclined to fulfill them and in turn, they are more likely to keep improving themselves.
I used to eat meat basically every single meal. Then I started small, had vegetarian dinners once a week. That was achievable, so I started doing lunch too. Next thing you know, I'm eating about 30% the meat I used to, and when I do it's usually chicken or seafood.
And it doesn't stop there.
My point is, if you want to inspire meaningful change in others, give them actionable goals. Don't ask people to quit cold turkey because that seldom works.