Download LeechBlock NG for Firefox. LeechBlock NG is a simple productivity tool designed to block those time-wasting sites that can suck the life out of your working day. All you need to do is specify which sites to block and when to block them.
Allows setting time limits on sites. To stop yourself from wasting your life on dumb stuff.
If I had the self control to not just unblock the sites or uninstall the extension, I’d have the self control to not go to them in the first place. :P