Power of concentration and muscular reaction can be impaired by even a single drink. So do not drive car even after one drink. Smoking Cigarettes smoking is habit-forming. It reduces the capacity of lungs. It can cause Cancer of Lungs.
Smoking increases the risk of heart attacks.
A lot could be written on this. Unexplained fear, trembling of hand, sense of apprehension without cause. Very frequent attacks of depression with thoughts about suicide. Sleeplessness and headache. Sense of worthlessness and feeling that life is futile.