Schedule in advance when you’ll use the Internet, and then avoid it altogether outside these times. I suggest that you keep a notepad near your computer at work. On this pad, record the next time you’re allowed to use the Internet. Until you arrive at that time, absolutely no network connectivity is allowed—no matter how tempting.
In a world where your work is the internet, define the sites that are of limits and write down next time you allowed to use them (social, news, mail)