First of all try to remove the source of distraction and force yourself to take only one thing at a time. Open a webpage and read it entirely, read a book from start to finish (not necessary in a single day), try to work on your tasks without background music or podcast. Eliminating the distraction usually improve productivity.
Second try meditation. You can think that is a "radical chic" rubbish, but it really works. Start reading "Zen and Japanese Culture" and "Zen Mind, Beginner's Mind" and try to practice meditation, maybe with the help of an expert. You will see an improvement on focus and clear thinking.
Third, take time off your pc. If you understand that most of what you doing in front of the PC is not valuable, just close it and go out, or read a book, practice sport, cook, etc. Learn to recognise when you're waisting time and do something else. Try to make time at the pc more valuable. Use it for coding and research, not much more.
Improvements take time and consistency. We're used to get everything fast, but your cannot buy self-improvement in a course or a book. So start with basic steps and stop complaining.
I remember there was an online graph some years ago, (not sure if was a node graph or a simple bubble diagram) that the user could zoom in and out and show the most used websites with the number of users. Or maybe was a ranking from Alexa, but I remember there was a possibility to filter the view by country. Someone remember the url by any change? Maybe is on archive.org
The pc era is over, and the smartphone one is about to end. Apple is already there. New techs are AI, robotics, VR, data science, earphones... What is the most probable field of interest for a new startup for a young Steve Jobs today?