The human body is a complex machine and each of its parts plays a very important part in its good function. Thus, it is quite hard to imagine how a human would have dealt without one or the other parts of its body. However, a capital importance in the body's good function has its brain. Even the most banal activities, such as walking or seeing are controlled by it. Due to its extreme importance, it is necessary to maintain the brain in good shape and make sure that nothing will prevent it from working normally.
Most people even try to accelerate the speed with which their brain accumulates information and makes connections. Even though increasing your intelligence is not an easy process, but rather requires long time attention and a very well thought schedule, it does not mean that ordinary people are not able to improve their intelligence. In fact, the brain will start working much better once all those factors which influence it in a negative manner are eliminated.
Among the factors which negatively affect the brain we can enumerate the lack of proper sleep, stress, smoking and drinking. These last two factors are by far the most damaging to the human body in general, and to the brain especially. Smoking decreases the amount of oxygen from inside your body, thus also diminishing the amount of oxygen which goes to the brain. Low oxygen results in improper function of the brain, thus less intellectual capacity. Even though on short run, people may notice a certain improvement in their intellectual abilities while smoking, on the long run, the effects of smoking are quite damaging. A non-smoker has more chances to increase their IQ easy and fast than a person who ingests daily tobacco smoke.
On the other hand, drinking has serious effects on the structure of the nervous cells by destructing their connections. This damage can be temporary or permanent, depending on the quantity of alcohol ingested and the period of time in which one has drank on a regular basis. When one stops drinking and smoking, the brain starts to recover gradually and thus starts working better, allowing more information to be assimilated in a shorter period of time.
Thus, if you want to improve your mental abilities and increase your IQ significantly, you should start by giving up your negative habits of drinking and smoking. You will not also think more and better, but you will increase the quality of your life.