I often find myself revisiting the same sites over and over again when faced with a tedious task.
This is counter productive and is just prolonging the pain :)

So I have found it to be quite useful to simply block these sites locally, whenever I feel they become a problem.

To manage my hosts file I use Ghost which is easily installed from the terminal using gem install ghost.
When a site is stealing too much of my time, I simply just block it by typing sudo ghost add facebook.com. Ghost will add the entry facebook.com to /etc/hosts.

After 2 or 3 times getting the Safari Can’t Connect to the Server, you will stop using that site.