I agree with what the others above me have said - It's normal - although if you feel you want to change your habits then maybe you should look into breaking the routine, have a back up plan for when you start to think about and set up some sort of reward system?
If you truly want to stop addiction - you have already jumped the first barrier by admitting that you are addicted to it.
Metallica has a post a few down from yours with links to videos on youtube that he says are an excellent resource for any addict... maybe you should take a look...
http://www.teenhelp.org/forums/f124-...phy-addiction/
Claire x