Why am i so tired all the time?

Impossible to say: Some possibilities include: you don't get enough sleep; you have a serious illness (heart failure or kidney disease for instance); you have a hormonal disorder (such as a thyroid disorder); you have a poor diet - don't eat enough, eat too much, don't eat enough vegetables and fruit; you have a chronic infection (such as hepatitis); you are on medication that is causing fatigue as a side effect...