I think when you own up , fully and with all self honesty, to fact that you have control of that switch and slam it home.
When everything may not hang in the balance, when /if you can imagine a situation with minimal damage or realistically contained and negotiable damages of a one off , or even a pleasant experience with no adverse effects and still know you won’t.
Good , bad or indifferent nondrinkers simply don’t consume alcohol, and I am one
Anybody can be one , AV is the only one that thinks it’s an actual ‘big deal’, but of course IT would