There's a certain level of denial that goes in to a lot of positive thinking in negative situations.
Personally, my initial thought-reactions to things are base, shallow, negative as can be, etc. I used to try to combat this, to replace it with something else, but I realised after a while this is a counter-productive thing to do and is most likely the very reason I had problems dealing with certain things.
Now I accept my "conditioned thinking" as something in me to overcome. Not accept it because I can reason it, or because it seems to get thrown at me by "my own" brain. To doubt every thought, even those I like.
There was a time when I was under the impression I could think my way out of anything, and paid a serious price for that.
The map is not the territory!
Like the ancient Stoics said, we have to agree to work with the suffering in life in order to overcome it. It's not like we WANT to suffer or invite it. But people who want to deal with a certain issue at least have to accept its reality. No amount of positive thinking will cover up the truth of our suffering and our personal struggles.
But we have to constantly recognise that there is a reality beyond our thinking, and it's there we can truly influence things. Thinking can sometimes be the enemy! Especially if we have a self-critical language of thinking that gears us against ourselves, which is all too common and dominated my perspectives until I was ready to accept that there's more to life than what I think.
"The greatest enemy of the truth is not a lie, but the belief you've already found it." - this is true in situations where our own thinking might be keeping us locked into cycles of suffering. It's what we think that prevents us taking the necessary further insights from nature/reality, or even from each other.
Incredible write-up! And I could go on and on and on down the many rabbit holes of relevant things here.
Embrace your negative thinking. Just don't get stuck there! And you're more likely to get stuck there if you try to just cover it up with yet more thinking.