I'm always tired and i want to sleep

I sleep well. Not waking up for 8-9 hours,but when i wake up i feel tired. I can sleep whenever you say. I have no energy during the day. I mean i have sometimes but im not full of energy no matter what.. . I have no will power to exercise and feel lazy all day long in my free days. What can be wrong with me and how can i fix it? Tell me your personal exp if you ever felt like tha.t