I'm always tired for no apparent reason. Is there something wrong with me or is there anything I can do to prevent it from keep happening?

Medical check up. It is not possible to provide and opinion without examining you and may be doing some lab tests. You may be anemic, have some dietary deficiency, chronic infection or most likely depression. You should consult a doctor for a proper evaluation.
Running on empty. Hard to keep running when you feel out of gas. How's your sleep? How rested do you feel in the morning? When do you start feeling pooped? How's your diet? These are a few of the things to talk with your doc about. Check anemia, thyroid too.