Addiction is a disease of the brain. Your brain is the control center of your body, affecting your thoughts, feelings, decisions and actions. Addiction to drugs or alcohol is hard because it changes the signals in your brain, which makes it difficult to feel okay without using the drugs. When you first take drugs you feel a high or a rush from the substance. But over time, the high is not as strong and you must take more and more of the drug to keep from feeling bad. This is what happens when you become addicted. Many people who are addicted want to quit and they think they can do it on their own.