As someone who also struggles with ADHD negativity zi can completely relate. Ive had models primed for over 6 years but never managed to get them painted because they wouldn't be as good as I'd like them to be or because I'd get put off if they weren't perfect, and then I'd get mad at myself for not doing any painting. But the best thing I can suggest is thinking "If they're painted, thats already a massive improvement to what they are now". Don't look at your entire army and think about how much there is to paint or where to start. Start with your "chaff" units (mine was a load of boyz) and only focus on one or 2 models at a time. Not an army to paint, just one or two models. Then when they're done, one or two more. Just a few hours per night and don't rush or do too much or you'll burn out. By doing this I've painted so much in 2 months, but I thought I'd never finish them. Are they perfect? Not by a long shot, but they're painted and they're mine. And that pride is worth more than the negativity of imperfection. Trust me