I considered this while writing it, but figured there's a fine line one must walk with a utility like this. If it's too annoying to disable, you won't use it.

Typically once I flip it on, I forget about it, until I actually try to check a site that's been blocked. I find that being unable to load a site or loading a local webserver hosted file injects just enough time to realize I should be doing something else.

Previously I wasn't in the "trick yourself" camp, but having used this for a while, I definitely am. Used in conjunction with the Pomodoro Technique, it's a really solid way to keep oneself on track.