I'll admit that I tend to get addicted to stupid, nonproductive activities. Like, not even nonproductive stuff that feels good, like reading or taking walks - I mean stuff that eats up all my time and leaves me feeling vaguely icky, like surfing the 'net (not emailing friends or looking up important things to help my art career...just, like, pointlessly puttering around).
I've noticed in particular that I get super-strong cravings to go on the internet whenever I'm at a tricky point in an art project: cycling continuously back and forth through twenty open browser windows keeps my brain occupied so I can't obsess on my (possibly failed) painting or guilt myself out over not getting anything done. It's a way of running away from my problems. I think a lot of people are afraid to spend time alone in their brains, for various reasons, and so they run away through similar methods.
There's a thing I do that helps keep me on track, though, and maybe it'll work for you too. I came up with it back when I was still at my job and trying to convince myself to do art in my spare time instead of wasting those hours on useless time-eaters. Here's what I do:
I wake up, and I tell myself: "This is your day, to spend however you want."
Now, obviously most days aren't really all mine; I might have a job to go to or errands to run or what-have-you. But this mantra still serves as an excellent reminder that once I've fulfilled my obligations, I can choose how I use my remaining time. I don't have to go on autopilot and end up Googling each former cast member of The Facts of Life to see what they're up to nowadays; I can make a conscious decision to do something awesome and life-affirming instead.
If I somehow fall into an endless loop of internet-related fuckery anyway, I can sometimes snap myself out of it by asking myself, "Is this making me happy?" The answer is invariably NO. Puttering around on the internet is compelling, but feeling compelled isn't the same as feeling fulfilled. This same "is this making me happy?" technique has also helped me to end some pretty bad junk food binges.
In conclusion: today is your day. How do you plan to use it? :)