I have been "fatigued" for 3+ years due to having children. Life goes on.
It isn't like that with disease.
The worse I've had is the complete inability to stand long enough to make a simple dinner, for example, and this was after napping and sitting most of the day. I'm lucky: Mine passed. Some people live with this day after day after day, and this is more similar to what folks with disease-related fatigue.