Great idea and execution, though the intentional switching is sometimes a little glitchy.

It would be good if in addition to the deep breath, there was also some additional, dynamic friction introduced. For example, the buttons ('I do not want to visit X' / 'I want to visit X') could shift position to a different corner of the screen each time the extension is displayed, in order to actively engage the user at the point of making the choice. As it is, I find that already I am in the habit of just waiting the 5 seconds then automatically clicking the 'I want to visit X' button, which somewhat undermines the goal of the extension.

This is my problem, of course, but adding a little extra, dynamic friction of this kind to the interstitial page after the breath would strengthen the question of whether I *really* want to visit the website -- and thus enhance the value of the extension.