Will could be the output of a previous state of mind - absolutely mid thought you have internally given yourself another input “right change subject”
Brain chemistry determining it must happen is a an explanation of your mind carrying out the output based on input see above.
Think of a computer idling along, sure in the background things are happening, services are running that we cant see which enables the computer to be on but that computer will be waiting in a constant until something happens .... it receives an input.
The very statement “Will could just be” says the rest of your perceived sentence/thought could be wrong? It could just be that we have Will or free will in the limited capacity that I keep trying to put across, it cant be disproven.
What you are describing could be a bug in the system as you earlier alluded too, the fact that those things do not effect everyone in the same way kind of suggests that but with any of them (I’m going to generalise them as a group to be a cop out as I haven’t experienced any of them so cant comment from experience but only offer my thoughts and I’d rather not upset anyone whose going through or gone through any of them) with some training or help with your thoughts can be broken.
The fact that they dont effect everyone and could be seen as a bug would kind of say it would be strange for every single mind on the planet to have a bug to stop ourselves in thought or to change thought. Which would point towards not bug, will.
We dont have limitations of mind we came from a cave we wouldn’t be this advanced if we did.
@the village idiot earlier in the thread said he was depressed and turned to mindful meditation to help and now he views the world differently and isn’t as bad with the depression. Mindful meditation is the vehicle he has chosen to change or try to change his outputs. Mindful meditation is an input, so are anti depressants but they carry their own risks. Point is he chose an input which works to alter output.
All you mentioned will probably have a root cause to kick out that output they feel stuck in but people who have all come out the other side will have changed inputs to get different outputs, if you read why do you choose a topic you could read any book in the world to feed the itch/output of needing to read?
I personally feel we have a choice based on outputs that are automatic but we can change outputs with inputs to a degree. We have free will in a limited capacity but it is their.