The Three Laws of Robotics according to Isaac Asimov are as follows:
1. A robot may not injure a human being or through inaction allow a human being to come to harm.
2. A robot must obey all orders given it by a human being except when such orders would conflict with the First Law.
3. A robot must protect it's own existence as long as such protection does not conflict with the First or Second Law.
So, in turn if I am smoking cigarettes and excessively drinking the robot must kill me because, I am bringing myself harm through it's inaction. Even if I order it not to the robot must kill me because, the use of the Second Law on my part is conflicting with the First Law.