If I had a free second at any point in the day I would end up checking Facebook or reddit. I just couldn't stop myself so I deleted them. I deleted the Facebook and reddit app from my phone and iPad. This helped a lot. I still checked both in the browser so I ended up deactivating my fb account. I also use Stay Focused which is a chrome extension that blocks sites after a set time. I put reddit and a few other sites on the list. I still check HN. I see this site as educational and I don't regret reading the articles.
I second that. GetFocusd is excellent at reminding you why you installed it in the first place. I blocked most of the sites where I waste my time: Facebook, Reddit, News sites and general nonsensical, but entertaining sites. I turn off WiFi and mobile internet on my phone or even set it to airplane mode in extreme cases.