If your diet is not balanced or if it lacks important nutrients such as vitamins, your body might not function well and you might get a cold easily.
Water carries the needed nutrients to the different body organs. If you don't drink enough water, your body might not function well and so you might get sick. See why you should drink more water.
When you sleep your body produces cytokines which are protein-messengers that fight inflammation and disease. If you don't sleep well, your immune system will become weaker and you might get sick often. See how sleep affects health.
Stress puts a load on the immune system and can make you get sick easily. If you are going through a stressful phase of your life, you might get sick more often. See the causes of stress.
Our hands usually collect germs as we do our various daily tasks. If you don't wash your hands well, you might pass the germs to your nose or mouth and so get sick.
If you don't brush your teeth well, the bacteria growing in your mouth might infect other parts of your body and thus cause sickness.
If you don't wear enough clothes when it's cold or if you take a hot bath then go out immediately, you might get a cold more often. Watch out for all the daily habits that result in a sudden drop in body temperature. See why my body gets cold easily.
If you have any problems with your immune system, you might get sick more often. Make sure you visit a doctor to check on your immune system if you doubt it's the cause of your repetitive sickness.
If you eat unhealthy food, your immune system might be affected in a negative way. Moving towards a more healthy diet can make your immune system stronger.
Vitamin D plays an important role in fighting colds and maintaining overall health. Make sure you are getting enough vitamin D in your diet and also make sure you get exposed to sunlight, for it helps in the absorption of Vitamin D.
Using drugs and antibiotics often can weaken your body's natural defense system, and as a result, you might catch a cold more often.
Improper diet or the consumption of certain drugs can allow heavy metals to reach your body and so cause various types of poisoning.
Unclean air can weaken the immune system and can also carry germs and bacteria. If you are not getting proper fresh air, you might get sick more often.
Thyroid problems can result in frequent colds, for the body might not be able to maintain the proper needed temperature for the immune system to function well.