I appreciate that you'll listen, so I'll try and break it down more, because you're missing an important part of what I'm saying.
There is no individual thought to choose from. That's the issue with what you're suggesting. What you THINK is a thought, or a categorized value (numerical), is really just a combination of neurons being active/firing while other related neurons are firing and connecting.
You may have categorized these patterns into symbols, but at their core, they're just patterns.
You aren't choosing individual thoughts, you're dictating the entire state of your body.
And, each "thought", as you describe, only means something in the context of the rest of your body. Remove the rest of your body, and it means nothing to anything.
So, you cant really choose any thought as better than another, because your ENTIRE body has an optimal setting that includes the "thoughts" you're messing with. You can fight against it all you want, but the entirety of your body WILL push to bring your entire vessel to its optimal state.
I've spent many hours meditating. Zazen is very wise to use, qigong is very helpful, and stillness is very strong as well.
I caution you to avoid thinking that your thoughts are negative. Youre saying that neurons in your brain shouldnt be allowed to connect. Maybe instead of fighting them, you allow them to connect ALL THE WAY to where they're trying to go, and then they'll integrate fully.
If you can get to the point where your aware of the sensation of the thought in your brain OVER the thought itself, or the symbol attached to it, then you will see that there is no such thing as a negative thought.