People do not choose to have anxiety.
Similarly, you can be sad, and not have depression. The thing that makes it depression is not being able to trivially drop it. If you 'have anxiety', and can flip it on and off at will, then by the clinical definition you do not have generalized anxiety disorder. That's very nice property of the DSM.
However, I would really like to know why would anyone "turned on" own anxiety if they have possibility to not turn it on. What are you gaining from that? Sounds like hitting own leg with a hammer. Even if you can do it ... why?
I've never seen a definitive refer to me specifically. It doesn't pass the sniff test.