I was addicted to pornography. The way I knew was by trying to stop for at least a week, if I could accomplish that, then it wouldn't be a problem. I couldn't make it past one day.
I thought, maybe access was the issue - so I deleted my browsers, and within a day was reinstalling them just to watch porn.
I was watching during classes, and I would go late to events just so I could finish watching a particular scene, or explore a pornstar's catalogue.
It was only after confiding in somebody that I realised how deep I had sunk (watching and paying for snuff and gore), and it was extremely tough to come out of that.
I still get the urge when opening a browser to muscle memory type in a site, and it's constant vigilance and self-discipline that has held me at bay, but the pull has never went away.