Anxiety - is it in the mind or body?

What does 'Anxiety' mean to you? Is it just a verb? The act of being anxious, or is it an actual physical or mental condition?

Many years ago, I'd have thought it was purely psychological, controllable, maybe even a weakness. I didn't really know I was a sufferer. In reality, my anxiety had always been there. At the back of my mind, looking for the bad in every situation, oddly enough, keeping me on my toes and driving me to deliver more at work. Although as I'd grown older I genuinely did care less about other peoples opinions of me. I still tried my hardest to maintain an ethical approach to management. Realising, that although the work was important, it was far more important to maintain healthy relationships with those people you worked with. That ethos, and the paranoia keeping me on my toes was quite a useful combination. I was successful at what I did. However after being exposed to some pretty unethical and, in my opinion, demoralising management treatment, my anxiety became worse. Unbearable in fact, and sadly unmanageable with every day life. Panic attacks at 4 am in the morning. Sleepless nights after sleepless nights. Depression at home and at work and yes, very dark thoughts about the purpose of mortality.

After almost a years absence from work for a number of reasons, I am far more aware of the conditions existence and it's effects. Although I'd be lying if I said I wasn't progressing, the one part that is still most apparent is the inability to completely relax. I've been diagnosed with a high level of cholesterol in my blood. 7.5. My diet isn't bad. Although I've cut down on saturated fat, I've realised my intake wasn't high anyway. The food we ate, isn't responsible. What may be affecting it, is my consistent tenseness. The fight or flight response has me in it's grasp most of the time. Although I'm aware of it, and I can mentally put effort into relaxing, it's only a matter of minutes before I notice tenseness somewhere else. The best way I can describe it, is like trying to push down both ends of a see-saw. Only it's a see saw with 20 different seats.
For the most part, during the day, if I am 'doing' this isn't a problem. But when I'm trying to relax, even just watching TV, playing a computer game, or reading. I'll notice my shoulders will be rigid, rock solid, then when I consciously relax them and go back to my activity, my legs will be tense, or my arms, or somewhere else. It's a constant frustration and I can only assume other people who sit down to do something to relax, actually do relax and don't feel the same tenseness?
It's exhausting and thats when the body just gives up. When I genuinely just have no effort or energy left, when reserves are at their lowest. I sleep. My body shuts down. No matter where it is, or what time it is, I can't help myself. Sadly, this is rarely 11-12pm.
It feels like at those times a shot of diazepam might help. A muscle relaxant of some sort. But as the citalopram is already on 30mg a day, and the zopiclone is on hand, maybe more drugs isn't the answer. Maybe it's in the mind? Maybe it could be re-programmed somehow? That's the challenge now.