Is it normal to be able to kick the habit like this?

I'm 20 years old and I've had some issues in my life starting in late 2008, which I won't get into. But after a while of depression, anger issues, and other things, it only got worse. In late 2009, I got pushed over the edge and developed a strong "screw everything, I don't even care anymore" attitude, and then I turned to drugs. Predominantly I was doing cocaine, along with pill popping here and there and drinking, but it was mostly cocaine that I was addicted to. It was a rough battle with the addiction I had to it. It only made my anger issues worse, I've been to the hospital, I started a fight with someone, I got fired from a job due to swearing at/insulting a customer, and all sorts of other horrible things.
I finally sat down and got lost in thought and decided to end this. I already knew it was wrong and it was ruining me, but then I decided to try to get out of the addiction. I thought to myself, well I'll probably need to enter rehab, but I really didn't like the idea. So I wanted to try to get clean all by myself. I thought it would never work and I would relapse within no time. It was a stupid idea, but I tried to do it anyway.
That was January 2, 2011 when I made that decision, and I've been clean ever since.
I have never had the urge to do cocaine or anything else and the addiction is completely gone. So here I am seven months later, doing better than ever with a great job and friends and family, who are all amazed at the fact that I turned this around all by myself. And now that I'm pondering this whole situation, I'm wondering, is it normal how I was able to just decide to stop doing drugs and it just..well..happened? I mean you hear most people talk about when they tried to go clean, it was such a struggle and they kept relapsing. But with me, I just decided to stop and I stopped and the addiction was gone. Is that normal or is there really something wrong with me? A year and four months of cocaine abuse and it just disappeared all of a sudden, think about it...

I'm not making any of this up so if anyone thinks it's bullshit, then don't even bother commenting. I want serious answers here please.