HIMYF

Lily: Ok, yes, it's a mistake. But there are certain things in life where you know it's a mistake but you don't really know it's a mistake because the only way to really know it is a mistake is to make that mistake and look back and say "Yup, that was a mistake". So really, the bigger mistake would be to not make the mistake because then you'll go your whole life not really knowing if something is a mistake or not (...) Does any of this make sense to you?

Ted: I don't know, you said 'mistake' a lot.

 

HIMYM S01E21