In this case, I only noticed that I even had a particular habit once the habit no longer functioned as such. It reminds me of this poem, which I wrote shortly before my second child was born:
We've moved into the dining room,
and Miles into ours,
to make room for number two.
And every couple hours,
I head to what was once our room to get
something no longer there,
then turn around, amazed by habit,
by what I live in, unaware.
Light Quarterly 50, Autumn 2005