In the past I've manually edited my hosts file to point time-wasting sites to 127.0.0.1, which is a small obstacle at most -- I can easily edit it back -- but is enough of a speedbump to remind me "oh, right, I'm trying to avoid that right now." This time I haven't needed to; I managed to become so frustrated with the fact that my queue was saturated with short-term rewards that weren't netting me anything in the long run that choosing not to visit the sites doesn't seem to require much willpower.

This leads me to wonder whether I could eliminate other influences I want to avoid by making myself sufficiently frustrated with them, but that seems like it would be an unpleasant skill to pick up.