Someone quoted from "39 Melochos p. 112":
> "Simple, non-strenuous activities that are done routinely
> and effortlessly by people as a matter of course  (without
> any conscious thought that the act is a beneficial act of
> preparation) are in fact not Hachono, even when intended
> for post-Shabbos needs." ...
> He brings Shmiras Shabbos K'hilchasa 28:81 as a makor.

To which R' Joel Rich asked:
> This is consistent with what I was taught but have always
> had a hard time drawing a circle around.  For example, is
> the measure "people" or the individual involved?

The distinction is actually even more subtle than that. Look at the 
SSK there (it's a long paragraph, with seven different examples), and 
you'll see that in some cases, he specifies that the act is done 
without any THOUGHT of it being for after Shabbos (as quoted above), 
but in other cases he specifies that it is done without SPEAKING 
about it being for after Shabbos. The nafka mina being a case where 
one is mindful of the hachana, but still careful not to say anything 
aloud.

I have not done this myself, but still, I'd suggest that interested 
parties should learn the SSK's makoros for a better understanding of 
these criteria.

Akiva Miller