Ask HN: How to increase organization without anxiety?

I am a big fan of Cal Newport, and I was just listening to his most recent book Digital Minimalism which has quite a few strategies for replacing low-quality digital distraction for high-quality leisure and social connection. Towards the end of chapter 6 he suggests setting goals and scheduling time for structured leisure, which sounds great but got me thinking about why that is so difficult for me.

Organization in the form of schedules, task lists, and deadlines has always been a major struggle for me. I received an ADHD diagnosis shortly before my 35th birthday, which explains a lot of that. I am also susceptible to elevated anxiety, which has never been severe enough for a diagnosis but clearly affects my life. There is definitely a relationship between the two, because my ADHD brain has taught me that I can't consistently rely on myself to stick to schedules and deadlines, so when I am up against those constraints my anxiety gets triggered. But on the flip side, I know that having more predictability in my life would reduce my overall anxiety.

For those of you who have struggled with similar issues: What organizational and planning techniques and strategies have you found that tend not to aggravate your anxiety, and thus are more likely to be adhered to? If you recommend something well-known (e.g. GTD) it would be great if you could explain specifically how you implemented it in a way to minimize anxiety.