Ugh. For me, anxiety manifests itself in the form for obsessive thoughts. Whenever Im stressing about something it plays over and over again in my mind sometimes for hours. No matter how much I'd rather not think about whatever it is. Sometimes i can distract myself with other things, but the problem is always lurking in the back of my mind. It fades eventually, but before I get to the point where i can put it behind me my mind makes sure I've gone over it from every angle.

I also have a tendency towards catastrophic thinking. Always assuming that something isnt going to go positively for whatever reason.