External factors like sickness and disease causing organisms in your environment are not the only things that can endanger your health. Certain habits and things you do contribute to the existing external factors that endanger your health. 

Depriving yourself daily of the appropriate hours of sleep, results in a weak immune system. A recent study by the University of Chicago found that men who slept 4 hours a night produced only half of the antibodies designed to fight off flu, compared to those who slept 7.5 - 8.5 hours per night.

Aside weakening your immune system, sleep deprivation also negatively affects your central nervous system, respiratory system, cardiovascular system and digestive system. It leaves the brain exhausted, makes it difficult for you to concentrate, learn new things and make decisions and impairs overall cognitive function. Most adult require 7 - 9 hours of uninterrupted sleep. So, if you know you are going to wake up early, you shouldn't go to bed late.

If you are someone who always sees the cup as half empty, someone who always expects the worst to happen, you should know that you are endangering your health with such a mindset. Pessimistic people tend to live more stressful lives than optimistic people. They tend to have a lower T-cell count and a slower immune response.

Pessimistic and depressing thoughts depress your mind and, eventually, your body. You should work at re-orienting your thoughts, expectations and mindset to make them more positive. Learn not to expect the worst for yourself.

Being optimistic is not just about expecting things to go your way (realistically it isn't possible for things to always go your way), but it's about expecting good for yourself while preparing mentally and emotionally for the eventuality of an unfavorable result.

The body was created to move. That's why there are so many joints in the body. Physical activity helps to boost your energy, helps your cardiovascular system work more efficiently, improves your mood, combats health conditions and diseases, promotes better sleep and controls weight and prevents obesity.

Physical activity doesn't necessarily mean doing high intensity exercises; it can just mean participating in simple activities that get your heart rate up daily. Go for leisurely walks, move around more at your place of work, walk instead of driving to destinations with a walkable distance, take stairs instead of elevators, basically stay moving as much as possible.

The purpose of antibiotics is to fight serious infections and diseases. Taking antibiotics too often, especially when you have a slight illness or few symptoms can cause your body to develop a resistance to these antibiotics. This will therefore make you vulnerable to more serious cases of these infections.

Research has shown that those who consistently take antibiotics tend to have a suppressed immune system and are likely to get very sick in the future from diseases and infections. It is advisable to take antibiotics only when you have bacterial infections and only as much as you have been ordered to take by a doctor. You shouldn't use antibiotics to prevent illnesses.

Occasional stress is a part of life, but being under stress day after day without giving yourself a break isn't good for your health. Consistent stress weakens your central nervous and endocrine systems, makes you more likely to have heartburn or acid reflux,  weakens your immune system, raises your blood pressure and increases your risk of hypertension.

Learn to relieve yourself of stress. Take a break, relax and do something that helps relieve you of stress on a regular basis. Your body will thank you for it.