If you have Generalized Anxiety Disorder (GAD), you're up against the same Anxiety Trick - you experience Discomfort, but respond as if it were Danger - but here, the source of the Discomfort is your own thoughts.
A person with GAD does a great deal of worrying. It isn't so much that you have a particular problem you worry about, because over time you'll worry about lots of different problems. It's more that you have the problem of worrying. Just like Panic Disorder is a fear of fear, Generalized Anxiety Disorder is worry about worry.
People with GAD get into a conflictual relationship with their own thoughts. Sometimes, they take the content of their worries very seriously, and fret about it. For instance, you might have the thought, "what if I lose my job?", and spend a lot of time wondering if your boss likes you or not; where you might look for another job; how you could find out if you'll be fired; how your spouse would react; and so on. You'd think about it a lot in an effort to reassure yourself, and find that you just get more worried.
Other times, you'd stop thinking about the idea of getting fired, and focus instead on how all this worry might affect you. You would worry that the worry will lead to a stroke, or a nervous breakdown. You'd be worrying about worry.
There are other symptoms of Generalized Anxiety Disorder - aches and pains, restlessness, sleep disturbances - but all these other symptoms seem to be caused by the excessive worrying.
There are two words which, much more than any others, signal that you're getting into worries. These words are "what if...?".
People with GAD imagine something bad (what if I get too anxious to work?), regardless of how likely or unlikely it is, and imagine the terrible consequences should this event occur. Then they try to figure out how they could make sure that this bad thing will never ever happen.
People with Generalized Anxiety Disorder want to make very sure that their bad thoughts will never become reality. They want to eliminate all doubt. Since it's impossible to prove, beyond a shadow of a doubt, that something could never happen, this opens the door to worry without end.
If you have GAD, you probably spend a lot of time trying to get your thoughts just the way you want them. You don't want to have any negative thoughts, and if you have any, you want to be able to prove to yourself that they can't possibly happen. You spend so much time and effort trying to get your thoughts cleaned up and arranged the way you want, that you spend less of your time and energy out in the real world.
The problem is this. If there was a rock or tree stump on your property, you could remove it, and that would be the end of it. The rock would not return. But if you have a thought in your mind and try to remove it, the very act of trying to remove the thought practically guarantees that you will have the thought again.
This is the problem with thought stopping, and distraction in general. If you tell yourself not to think about dandelions, you'll probably be seeing plenty of them in your mind. The more you try to suppress a thought, the more it tends to return. Objects won't return when you dispose of them, but thoughts will.
Since you can't simply "turn off" thoughts, progress with Generalized Anxiety Disorder (and with worry in general) comes when a person becomes more accepting of his thoughts - the good, the bad, and the unlikely - rather than opposing them. Effective treatment will help you change your relationship with your thoughts. It will help you respond to them as nothing more than symptoms of anxiety,rather than treating them as important signals about your future. One of the best ways to make this change is the use of worry periods.