1.Smoking
2.Alcohol
3.Eating without exercise
4.Drug abuse
5.Excess intercourse
6.Constant consumption of a class of food.
1.Smoking:smoking is the intake of acidic air from cigarette that goes directly to the lungs which will later go to the blood stream. a large number of the people living on earth are smokers, both male and female. most of them are lads that know little or nothing about the dangers of smoking. like i said earlier on, smoking is a life span reducer. cigarette is a product that is hardly advertised and most makers of cigarette always give a warning against smoking, this is to tell you how dangerous and unhealthy smoking is. most diseases have their roots traced down to smoking, like heart attack, cancer of the lungs e.t.c.
2.Alcohol: taking of alcohol once in a while in little quantities can be a little safe but when it is taken regularly in large amounts, it can be very dangerous and hence become a serious problem. if you're that type that can drink up a truck load of alcoholic wine or rum, then you need to drop such habit, if the need arise then you should just take a little (don't take at all if you can). alcohol just like any other bad habit has a way of breaking down the pillars of good health. the more you take, the more you get addicted to it and when you get addicted to alcohol that's the beginning of the end of good health for you.