Ive just been reading a friends blog - and he had this link on his site to information on CFIDS/M.E. It's quite comprehensive and explains things far better than I could so I've copied the link to add here in case people want to know about it.
another good site for an explanation is
This is a good site for some helpful keys to deal with coping and on how to live well with long-term illness such as Myalgic Encephalomyelitis. can be aplied to other situations also like cancer or sim things. Much of it is practical and constructive.