Wow. At the risk of sounding condescending, please go look up the definition of 'addiction' before you so loosely apply it.
I hate to be the downer in the group, but if you're going to say 'addiction', I will hold you to the strictest definition of the word. If you want to be cavalier about it, don't even use 'addiction', and stick to 'what can you not do without?' because addiction, as I'm sure many of you will eventually find out, is a horrible *****-goddess who can quite easily destroy you.
Little splash-of-cold-water-in-the-face here, but you take that attitude into real life where you're dealing with others who are totally serious about their inability to deal without something, they are... not going to respond well to your... youthful vigor.
Now to answer the question? I am unfortunate enough to have an addictive personality. I've overcome most of them, but currently on the docket is booze. It's really difficult as it is such a socially-accepted vice in the States.
Many of you will probably be lucky enough to not have that trait, but even then, just remember that sometimes the key to success is to never stop trying. That applies to overcoming addiction as well as most other difficult endeavors in life...
I'll stop being a total downer now...