What I did was to write in every site that I go to on a regular basis that I KNOW are very time consuming once I get started.
Now, every once in a while, when I do realize that this or that consumes a lot of time, I add it. It's not always on. I allow myself some time to browse and waste, but when I say to myself : Okay, enough, now is the time to get things done, I turn it on. And I at least get the ball rolling.
Don't kid yourself though, we all have smartphones or even tablets, and I am no exception. If I wanted to really do something else, I could. (And sometimes do)
Has this little app changed my life ? No.
Did it have any positive or negative effects on my productivity ? Only positive for me. And of course, we could use proxies, but at that point, you might just not be commited into taking action.
My problem is procrastination. Not being lazy.
If I want to work, I end up thinking it through too much, or wanting everything to be perfect, I waste time trying to improve my knowledge about a topic, instead of doing something (even if it's not perfect).
This application helps if you are like me.