Cures for tiredness?

I always just assumed it was because of my ADHD or other mental stuff, but I am always tired no matter how much I sleep. I've had this problem since about puberty and doctors can't give me an answer. I just find it hard to be motivated. Everything is a huge effort and I find it hard to keep on top of all the shit we need to do to maintain our lives. I am so sick of having to constantly cook and clean and maintain things. Everything is such a slog. How do you people find the energy to do anything other than work? By the time I've finished my University work, I can't be assed doing anything else.