What helped me most is a high protein/low carb diet, sunshine + exercise (can be just walking), regular sleep hours and anti-inflammatory herbal supplements. Too boring? 🙂
Ok, let’s try again. I have a family member who is primarily hyperactive and not really inattentive, and it’s a different beast than primarily inattentive me. He notices everything but cannot look at a single thing for long, is impulsive and impatient, has a tendency to gravitate to the next “fun” thing without long term planning, initiates projects easily but has trouble with finishing details, and needs constant physical and psychological stimulation. Other family members with a high inattentive component tend to get overstimulated easily, are significantly less impulsive but more stubborn and cautious (even anxious), and seem to be derailed less by the next “fun” thing but have more trouble initiating projects. Experts feel that ADHD is an umbrella diagnostic, and I personally believe that totally different mechanisms underlie the inattentive and hyperactive components.
The good news is that most experts focus on the inattentive components because they are more trouble. (May be hard to believe, but a total lapse of attention can be infinitely more dangerous than a roving one. It’s not only that you don’t know where you are and what you are doing, but your brain loses track of what your body is doing also. A roving attention allows you to react to stimuli very fast.) Also, a lot of advice on how to set up the environment is given for easily overstimulated people, and is likely to drive an understimulated person catatonic. Here is what helped, in my experience: a stimulating environment filled with meaningful items/projects (visual stimulation), music (auditory stimulation) and people, physical exercise that raises the heart rate, and also anything with skin contact (martial arts, swimming, sex etc.), a higher protein/lower carb diet (sorry, there is no escaping the fact that insulin spikes harm brain functioning in everybody), no alcohol (sorry again, but alcohol is a depressant and your body needs more stimulation not less — feel free to load up on caffeine!), and a reliance on an electronic calendar that you can see a month at a glance (everything goes there, and prevents the worst derailments). If looking into the future for long term goals is too excruciating, the “small steps” technique can work wonders — see Mini Habits: Smaller Habits, Bigger Results by Stephen Guise (https://www.amazon.com/Mini-Habits-Smaller-Bigger-Results-ebook/dp/B00HGKNBDK). It is written in a sectional, concise format that would make it easier for you to go through.