Well, not sure I'd call it a chore... but we make sure we dtd when I O. If neither of us are really in the mood, we joke about how this time is purely for reproduction purposes. It's very in and out (pun might've been intended there...) But it's discussed in a very light-hearted/jokey manner.
We still enjoy dtd when we're not trying, but we both get so busy and I go to bed much earlier than DH, so it's very easy to not carve out time.
So when I O, we just make sure we make the time as apposed to waiting for the mood to hit us.