How can you stop yourself doing things you seem to have no control over?

I hate this so much yet day after day I go back again and again, despite the fact it makes me feel like crap and don’t know what I’m getting out of it at all… it’s like impulsive and i know consciously how much better it is when i don’t and know how good it feels, but it’s like there’s some small dude in me somewhere that stops me thinking and makes me do what he wants D= so what can i do? I tried so many different ways to try and avoid myself going back again but nothing works… D=

ps. no heroin or similar involved =]