Addictions are more common than you might think, as the brain can be addicted to a variety of things, including dieting, substances, pornography, shopping, sex, and adrenaline. There has been groundbreaking research on neuroplasticity in recent years, which shows that the brain can learn new patterns, heal and change itself in response to trauma or disability, and that repeated behaviours help to form pathways in the brain, making it easier to repeat the same action.
A person who has an addiction forms certain neuropathways in the brain. The addiction begins with choosing to act in a certain way, but it then develops into an impulse that is uncontrollable, an urge that is hardwired in the brain. This is the point where addiction is no longer a choice, but an impulse. Think of the brain as a forest, and as an addict, you walk down the same path (or neuropathway) over and over again. The path is easy to walk down and free of branches or obstacles because you have taken this particular path so many times. It is the path you are used to, and it has become second nature.
The latest research has shown that it takes time and repetitive changes in our behaviour (freedom from the addiction), for the brain to heal old neuro pathways and form new ones. This is why detoxification, or long periods of time without exposure to the drug, or other addiction, are so important. You must give your brain a chance to be free from the behaviour that supports the neurological structure. Imagine, the forest path (the pathway of addition), growing over because you are no longer walking down the same path. The new path you are taking is hard at first, although it is the right choice.
To become free from addiction, you have to create a new route through the forest, and it may be full of obstacles. You have to force yourself to take this route, pushing through the trees and foliage. It will be difficult at first, but eventually, the new path starts to look like the old one, free of obstacles and uncertainties. When you look back at the old path, it has grown over and seems like the more difficult choice. The old urges you have may always be there, but they will fade. When you continue to choose the right path, it becomes easier with time.