Another great resource for adolescents with anxiety:
website from the Annenberg Center at UPenn:
www.copecaredeal.orgthis page with info on anxiety specifically:
http://www.copecaredeal.org/MZ_Articles.aspx?Condition=1books written for parents about specific mental health issues, including anxiety:
http://www.copecaredeal.org/Articles.aspx?Theme=TheDeal&ArticleID=105books written by young adults who lived through mental illness in adolescence, and continue to cope with it as functioning adults:
http://www.copecaredeal.org/Articles.aspx?Theme=TheDeal&ArticleID=104These are all freely downloadable books (I have paperback copies of them from a couple of years ago, and I think you can still buy paper copies, if you prefer.)
The above resources are largely written with adolescents as the direct audience, and, I think, are particularly helpful for high-cognitive kids, who need more information about their diagnosis to accept and manage it.
I would highly recommend that you look into cognitive-behavioral therapy. It has a good evidence-base, unlike most MH therapies, and can be the difference between meds/no meds, or at least a lower dose of meds.
A lot of my students with anxiety run (especially outdoors), lift weights, do martial arts, etc., as a coping mechanism. And I would reiterate that it is really important to take care of basic needs well, and to leave enough space.