Why can't i quit heroin?

Addiction to Heroin: Your brain has receptors that when given an opioid medication, heroin, morphine, hydrocodone, will be stimulated, which causes as cascade of Dopamine down the "reward pathway." for some individuals this is very strong, and they crave multiple doses and stronger doses, leading to addiction. A supportive treatment program that includes detox can get you going the right direction.

You have a disease: This disease is called addiction. Horrible physical withdrawals but even past that long term chances to brain that make stopping difficult. Long term cravings and not finding much fun in anything else. But with support and not going it alone these things get better, rehab, 12 step meeting, counseling and certain medication to help with craving and withdrawals available. Talk to doctor or therapist.