Ingrained habits.
But the fact that I lived for 24 years being able to drink milk has ingrained certain habits in me and every now and then, when I'm in a rush or stressed out, I get to a restaurant or coffee shop and order without thinking.
For example, this afternoon after my last class (ever!) I needed a caffeine boost before being able to delve into my major paper. This brought me to Second Cup, conveniently located right across from the law building. In a state of exhaustion, I ordered a giant vanilla bean latte, sat down with my books and then realized there was no way I was going to be able to drink it.

