###Human: I have been feeling tired the whole day. I do not really want to do anything and I do not know why. ###Assistant: Hi. No need to be worried, but yes you need to get evaluated for the cause of your problems because at the age of 18, tiredness all the day and weakness is not common. Your problems could be due to low hemoglobin, vitamin D or B12 deficiency, or due to thyroid problems or diabetes. I advise you to get the following tests done: