Sometimes I experience similar things. The definition of a projection is very fitting.
When we are really sad, we project this feeling towards everyone and everything. Regardless how good something is, we will see the negative sites of it.
I mean we truly were put on this earth to suffer if all our brains can comprehend is sadness and suffering. To the point where we can't even hear the happiness in happy music, our brains can't even comprehend a good feeling.
I've been told that I'm "choosing to be sad". The question is, why? How can I prefer sadness over happiness? Maybe I've just never associated happiness with safety, and my fearful brain chooses the sadness that is comfortable. But that's not really true either. I'm never comfortable. I'm constantly on edge, nervous.
Such mysteries. I approach happy people with the attitude of learning what they do to achieve what they want. However, I quickly make even the happiest people miserable and anxious with my mere presence. They respond with hate, because I took away their happiness. I never get any answers from them, as it appears they have no answers, only questions for me and commands for me. The solution, I believe, is to stop thinking.
But how do we stop thinking?
You are probably used of being sad. It's your normal "working state". So you subconsciously choose sadness. When your perception of life is very negative, then you will create more and more negative things.
One problem, as you said, is constantly thinking. I am also a very much thinking person. Thinking about the same topic over and over again won't do anything, but to reinforce the problem. The more energy you invest into this topic, the more energy the problem receives and the mountain infront of you gets bigger and bigger.
I found, that doing a STOP is the best thing.
If you recognize you are in a thinking spirale about the same topic, then STOP. Do something different. I know it's difficult, you want to find the solution for the problem. But the solution may only come with time, not with thinking.
The moment we leave the sad emotional state, we are more open to new directions.
I would encourage you to stop watching other people, how they achieve their goals. All the YouTube videos, where successfull people explain, how to reach your wishes don't really help. I know what I write about, I watched many of them
Simply relax, distract yourself with something different and life on auto-pilot. The time you have a more positive general percepion, the easier everything will get.
But stopping the thoughts and relaxing is the hardest part of everything.
I feel with you and I hope it was a bit understandable.