When your husband says, "I'm going to stop at the shop on the way home," and you know exactly which shop that is.
When you buy an "All the Nitrox you can eat" card, and the dive shop owner turns pale when he sees you come in.
When you put yourself to sleep every night imagining that wonderful moment when your head slips under the water.
When your dive buddy is all excited about a cute chick he's met, and you ask him, "But does she dive?"
When you are touring Amsterdam with your in-laws and you find a dive shop and go in just to breathe for a few minutes.
I'm guilty of all of the above.