Pauses. I am experimenting with basic scheme of 25 mins focus and then 5 mins pause. It is mind blowing how it lowers frustration and sort of ensures that I start work only on a clear task which I often tend to loose to easily.
The biggest surprise are the pauses (no, no email checking or web browsing; get up and move around). While formerly I experienced it that I don't have enough time to do what I want to do, I experience just the opposite of it during pauses. Now, what do I do in this time? Wow. That's new.
But also hard to stick to it. But there is more to it, the rules and principles that go along with it.
Sounds like the Pomodoro Technique [0] (also mentioned in the article). Glad it is working out for you!
I tried that to help with my ADHD with very little and very fleeting success.
The classic Pomodoro is said to be 25minn + 5 mins break, which adds up to half an hour, which is a common measurement unit for time worked. I've discovered that for my needs, a 20 min pomodoro with 5 mins rest works better.
The problem is that Pomodoros are hard to count if you hit flow state and find it hard to stop when the timer rings.
To add a data point, I used to do Pomodoro timing (25+5 min) but now switched to 15 min timer with a loose 2-5 min break. It's still hard to actually pull out of hyper-focus/anxious perseveration sometimes, but the shorter timer period seems to match my task cadence better. And the non-timed break just vibes better because it doesn't feel like punishment then.
