Challenge HN: Restrict a dev (me) to browsing Stack Overflow & Google redirects

Problem: I'm very ADHD & terribly undisciplined. The last three counselors/coaches I've been to independently deemed me the worst case of adult ADHD they'd ever seen (without knowing others had also done so). I'm building out a comprehensive management plan for myself and one of the things I desperately need is a way to prevent distraction by going to off-task sites. In a few weeks, I'll be attempting to change multiple habits at once and it feels like this habit may be one that I can simply nullify through some tech solution.

Solution: Block all websites I don't need when working. To start with, I figure I'll only allow myself to have access to Stack Overflow & anything redirected to or referred by Google. In an ideal world, I'd be free to add (but not modify/delete) sites to a blacklist. Modifying the blacklist or whitelist would require someone else to allow it.

Difficulty: I'm rebellious, even against myself. I'm also a tech-savvy coder. If it takes less than 5 mins to bypass or disable the blocking mechanism, I'll probably be able to figure it out and won't hesitate to use it. If the code required to automate the bypass can be done in less than 100 lines, chances are I'll write it. Since the goal here is to minimize the effort involved in curbing this habit (to make it easier to focus on changing other habits), the solution needs to force me to stay on task instead of simply training me to.

Also, keep in mind that I'm a developer and there are 3rd-party systems I need to be able to access outside of the browser.