I'm not the most qualified to answer this but...
- Reduce distractions. Pay attention to the things that break your focus and aggressively mute them.[0]
- Treat yourself like a plant, not a machine. You need the right conditions to grow. This means good sleep, good nutrition, and the right setting. This affects your focus.
- Consider that some approaches might not work for you. Not everyone learns well in a classroom. Explore other ways of achieving your goals. Alternative work arrangements could suit you better.