I have quite a lot of energy, but I know some people just aren't as lucky. Is their a medical condition for being constantly tired?
I think it's called Chronic Fatigue Syndrom, or CFS.  I don't know a lot about it, but it makes people tired for long-term amounts of time.
That must be awful. I wonder what causes it. Depression perhaps?
I don't think the cause is fully understood.  It could be genetic, could be biological, or it could be psychological.
Well, I guess the medical profession had better get to the bottom of it. It must be destroying people's lives!
I'm sure it is, but people are starting to see that behavioral therapy and a slow increase in activity can help counteract the effects.