Funny how our minds, in the worst times, starts a story that we never even ask for. When we are happy, it starts to show us of times of sadness and loss. When we are stressed, it plays out an even worse saga. It makes it seem like it has something against our peace and calm.
Well, I can tell you that this is because you have not taken the time to train your brain. It has gone by doing whatever it wants without supervision. If you want the endless worry and pessimism to stop, you need to show your brain what you want to see instead. Do affirmations, pay attention! When you start seeing that negative movie start to play, have something ready to think or say instead. When you due the work your brain will learn to shift any frequency any time it starts going negative.