ADHD

See 2nd half of the post for some tips.

I'm going to echo what some others said: medication is usually effective and often so much so it feels like cheating. I know you've mentioned it's impossible to get it where you live, but it's very likely you are wrong about it:

Several years ago I moved back to my home country (Poland) only to learn that according to local regulation there is no such thing as an adult with ADHD. They reluctantly admit that ADHD exists, but only as a childhood condition. On top of that most doctors don't like or straight up won't prescribe anything psychoactive, even antidepressants. It took me a while to find a doctor that would prescribe me the meds I need, only to learn that what I was taking for years was not available in the country, so every 3 months I've had to go through entire target import procedure to get 90 days worth of pills.

It's hard to get those meds in many countries, but people who need them and manage to get them share their experiences. Do some searching and you might find some help.

General tips:

• try to do small tasks immediately when you learn you have to do something
• if you can't do something immediately write it down. anything not done or written down immediately has been cast into the void ;-)
• always carry a notepad and something to write on you
• increase friction of switching to something else. Sit down at an empty desk to do work, so you have to get up to do something else. Keep your phone in a pocket with a zipper, so you have to unzip it to take it out
• minimize impact. I tend to put down whatever I'm holding if distracted and completely forget where I put it, so I put an easily accessible catch-all bowl in every room. Most of the time I only have check the bowls
• routine is your friend, it makes it harder to get sidetracked and increases the part of your life that happens on autopilot
• if you see you are getting things done keep the flow going. don't reward yourself with a break until you are ready do nothing productive for the rest of the day

Working at a desk/on a computer:

• remove absolutely everything from your desk that you can. ideally it's mouse, keyboard, monitor. avoid having any snacks on the desk too.
• if you have people walking around you or behind your screen move or try to block them. A cubicle is surprisingly ADHD friendly
• block sound distractions. listening to regular music might not be a good fit here, but myNoise or focus@will works great for me
• phone in a pocket/purse. notifications off. if it has to be on the desk put it as far to the side as possible and screen down
• if you have people at work who are constant distractions have a serious conversation with them. after that conversation every time they interrupt what you are doing make sure to remind them: "I told you it's going to take me half an hour to focus again, please be more mindful of that"
• disable all notifications and if you have to have them enabled set up filters to minimize what you see. Surprisingly in most workplaces checking you email 1-3 times a day is more than enough