Obsessing over what bothers you? In anger management class, they taught me that was also called "negative self-talk." That's where you mentally reinforce a negative thought by repeating it, over and over.
For example, let's say my boss yelled at me. (My current boss would never do that, but the previous one did.) That's unpleasant, but negative self-talk can make it worse. I can start brooding, and thinking to myself "he can't talk to me that way" and "I'm going to tell him to take this job and shove it." Instead of just briefly letting those thoughts flicker through my mind, I can obsess over them, keeping my anger simmering steadily, thinking to myself all day long, "he can't talk to me that way." Then the next time I have to talk to him, it's a dangerous situation. At the very least, he may notice that I'm tense and irritable. At worst, I might blurt out something regrettable, like "you can't talk to me that way" and then lose my job. Right now would be an especially bad time to lose my job.
So one way to beat the negative self-talk is to flip the script and do positive self-talk. Try hard to think of a positive spin to the situation, and then repeat those positive thoughts like a mantra. Think to yourself, "she's a good person" or "this isn't a big deal" or "I feel fine."
That said, you should also deal directly with the problem at hand if you can. And if this is about the situation you've mentioned in other threads, you can.
Good decisions come from experience. Experience comes from bad decisions.