“Oftentimes you are experiencing dread without any real external triggers whatsoever, providing no readily available, preferably small threat that you can safely attribute it to.”
Again, I doubt this actually occurs that often. My prior is that there is some trigger whatsoever in most cases. Perhaps it is better not to try to find a cause, though, if you think it most likely you’ll turn up something false.
I’m not recommending you try to dispatch with your anxious feelings through (mis)attribution. When I realize something like jealousy is keeping me tense and distressed, usually the real (still unpleasant) feeling comes to the fore and fight-or-flight recedes on its own. But sometimes I realize what’s happening and still feel anxious, just more mindful and not spinning off into false attributions as much. I’m not recommending you seek the relief of an answer to soothe yourself, but rather that you remember that, when you are feeling anxious, your body is preparing you to deal with what it perceives as a threat. With mindful observation, it is often possible to determine what set off anxiety and led to the cascade of imaginary threats. And very often, thinking about the perceived threat consciously cuts it down to size.
The true thing that is threatening you may not be insignificant, and may feel really terrible. But we don’t call it anxiety if someone is having a totally proportional reaction to their problems.
I see what you’re saying about false attributions, which seriously exacerbate anxiety, but I’m talking about piecing together the actual series of events that occurred when you became anxious, not the things you subsequently started worrying about. I actually don’t think feelings of chronic anxiety have no proximate cause and come up out of nowhere. Of course no one knows this for sure, but my belief based on the high efficacy of CBT for anxiety, my experience with CBT and Buddhism, and my own introspection is that thoughts are the triggers and sustainers of chronic anxiety. Most people can learn to identify the thoughts that sustain their anxiety and see for themselves that they contain cognitive distortions. Furthermore, I believe that the anxious feelings that call up the thoughts usually do come from some external trigger, however subtle. Being on your commute where you’re normally stressed, someone giving you a confusing look, or having feelings you’re not supposed to have (like jealousy) can be enough to get an anxiety storm going.
For any particular instance of anxiety coming “out of nowhere,” my prior is now that there was an external prompt or trigger. I’m not saying anxiety was a called for reaction (if it ever is), but it was the reaction to something that you perceived as a threat to your safety, status, self-concept, etc. Often the trigger is so small that you don’t consciously notice it, drawn instead by anxiety’s slight of hand to worry about health, safety, all the things you listed.
Maybe the threat reframe doesn’t work for you, but for some reason it does for me. When I ask myself what’s threatening me right now, the answer tends to be more real and immediate than when I ask myself “why am I anxious?” and get a bunch of general reasons that might justify feeling distressed. I think the threat question cuts through a lot of the shame I have at feeling negative feelings towards other people. I believe my anxiety results in large part from wanting to avoid and not to have to acknowledge those feelings. Reminding myself that I’m perceiving my natural feelings and reactions as threats helps to check one of the most common causes of my anxiety.