I think I have what you call "Generalized Anxiety", but I think it's a bit different from just worrying. If you have Generalized Anxiety you just feel anxious very often (agitated, uneasy, stressed out) even though you are not really worrying about something explicitly.
In any case, whatever it is, I know there is always a cause. I have noticed that the real reason why I am always anxious and worried is that I am too pessimistic and I have no self-esteem. That causes me to assume everything is a threat, and once you do that all the time and you keep worrying about everything, it becomes a f*king bad habit. But the real cause seems to be something, like no self-esteem or something like that. If I have to go to a mall I will probably start to feel anxious just after I have thought of going, because I am probably unconsciously thinking "if I go there I will feel bad, everyone will look better than me, they will look at me, I will feel horrible, I will look clumsy as always, I hate that place". So when you are convinced of that, you are biased, that's your unhealthy deep belief, and being anxious will be an automatic consequence.
That's what I've understood so far.