I am a worrier. In fact, I got about four hours of sleep last night, because when I woke up at 4:30 this morning, worries about training the new boxer immediately started racing through my head. What I call the hamster wheel began turning: I would run through the entire list of concerns and then start over again from the beginning--over and over again.
What to do about it? Since I think worrying is one of the stupidest pursuits of humankind--what good, after all, does it do?--I try to apply heavy doses of reason to the affected area. While not entirely effective, this treatment does help, especially if used consistently.
Method: Every time you notice yourself worrying compulsively, firmly but gently remind yourself that you're being an idiot. Usually, this will stop you for a moment. Very quickly, however--especially when you first try this--you'll get on the hamster wheel again. At that point, reprimand yourself once more. Repeat as necessary. Believe it or not, if you do this consistently, it will make a difference. Eventually, you will be able to halt the compulsive behavior more quickly, even though you will probably never eliminate it completely.