The key to a massive increase in productivity lies in dopamine starvation. By limiting the dopamine sources you encounter in your daily life, you'll be able to deprive much more enjoyment even from mundane tasks.
These can be simple changes such as staying away from social media and not listening to music/podcasts.
You'll see results extremely fast.
It's also a huge motivation to get things done that you might have been avoiding (such as cleaning).
Just try it for a few days or maybe even a week.