Feeling tired all the time stems from a wide variety of things, such as the pressure of everyday life, rigorous physical activity, as well as certain health conditions. According to mayo clinic, anemia, diabetes, heart disease, obesity and thyroid issues can make you feel exhausted the whole time. Yet, cancer is another reason for persistent tiredness you should not ignore.
As a matter of fact, certain types of cancer, like leukemia and colon cancer, can be the culprit of persistent fatigue. So, if you feel more tired than normal, or for an extended period of time, call your doctor immediately.