I don't usually find that lying is necessary in situations like this.
For example, when I'm at my lowest, my usual response to "How are you?" is "Eh... been better. You?"
No doubt there are communities in which even that is too much actual information; I don't hang out in such communities by preference, but if I found myself in one I'd give an even less informative answer.
As for what to teach kids... well, beats me, but I will say that knowing when a question doesn't merit a complete and exhaustive answer is a social skill worth learning.