Fatigue and shortness of breath can be caused by many things. Lung conditions and respiratory illnesses tend to cause most cases of shortness of breath. General fatigue can be caused by a wider variety of issues.
When airways in your lungs constrict and inflame, it can make it increasingly difficult for you to draw in sufficient amounts of air. This is asthma, which is chronic and can be caused by environmental or genetic factors.
When your lungs become infected with a foreign microorganism, inflammation can result and cause pneumonia. Bacteria, fungi and viruses can all potentially cause pneumonia. If your lungs feel particularly heavy and you are finding it increasingly difficult to breathe, this lung infection might be the reason.
If you are stressed by any of life's recent events, experiencing this stress for longer periods of time can cause your airways to begin to constrict. You may find that your chest feels more and more tight if you are experiencing intense feelings of anxiety.
Lack of Exercise
If you do not exercise regularly, additional weight gain can contribute to a chronic feeling of shortness of breath because of the extra weight that your body is carrying. Being overweight may also predispose you to feeling tired more easily when you are doing everyday activities.
If you're older and finding that you are becoming tired and feeling short of breath doing activities that you used to do without a problem, this may be why. Fatigue and shortness of breath when doing reasonably easy activities are usually the first sign that something is beginning to go wrong with your heart.
If fatigue and shortness of breath begin to surface immediately after you have eaten something, you may want to consider a food allergy. Insect bites can also cause these reactions, as can allergic reactions to medication.