Fellow adhd writer, how do I stick with a single topic and finish it? I could always manage my academic papers well enough but I’ve been trying to write fic for the last few years and can’t ever seem to finish one before another idea grabs me and I keep following one idea after the other
So, the way I manage that, is I often have more than one project going on at once. Being able to alternate between them provides my shiny crow brain with enough stimulation and variety to prevent me from getting bored.
I also keep a word document of "random thoughts that won't leave me tf alone," where I scribble things down to get the idea and impulse to follow it out of my head.
If I still can't stop thinking about it, I'll start planning it out. Devoting that level of attention to something will do one of two things for me. One, I'll have the outline for my next WIP done, or two, my brain will go, "aw, you want to make this into work?" and drop it like a hot potato.
To make progress on current projects, I set small daily goals. On average days, my minimum creative word count is 500.
Which, by the way, is often on par with the goal professional, award-winning writers set for themselves. Being able to write tens of thousands of words in a day sure is a thing some people are capable of (I am when I'm hyperfixating), but it's not sustainable, and you may be setting yourself up for burnout--especially if you try to maintain it longterm.
On bad days, I will reduce it to "okay, let's do a half hour and see how far I get." If I'm able to trap my attention, great. I'll keep going until I meet my goal.
If I can't, I accept that today is a low-attention day and acknowledge that I likely need more sleep, food, or stimulating recreation to give my brain both a rest and a boost. I do not consider these lost or failed days. They are all part of the productive, creative cycle and necessary. This is true whether you are NT or ND.
Body doubling can also be very helpful for those of us who work better with others present. I do body doubling with friends or people in my Discord sometimes. (Starting that up again soon, folks, just as soon as I get the okay to start working more from the eye doctor!) So if that sounds like something you'd enjoy, try asking friends if they'd like to set time aside to write together. Shared productivity can be beneficial for keeping ADHD and other flavors of ND on track.
If you lose all interest in a project. Shelve it and follow one of the other WIPS. Sometimes you need to be in a better place to work on certain things, and that's okay.
Some people thrive with a stricter structure than that, but this is what works for me. Small goals, allowing myself the time to follow diversions (while also trying to meet daily goals), and taking the time out to ensure I'm getting enough good stimulation in other ways. Took me a while in therapy to figure out a healthy work-life balance, but that's mine.
I hope that helps or provides a greater sense of solidarity.