With M.E. any periods of not-complete-awfulness are spent trying to catch up with the world (job, friends, driving, etc).
Even when I'm starting to see improvement (finally), and believing there is hope (finally), it is so easy for it to be ripped away again. I spent most of last week lying down or asleep; not watching anything, not listening to anything, only getting up to go to the toilet and get food (and I know I am lucky every time I am able to stand up) - in general I just existed day after day, waiting for life to be able to try and catch up with the online world (as I have already fallen so deep I no longer know if I can ever catch up with the real world).
Obviously I'm lucky that not every day is this bad any more, but M.E. means that for the rest of my life any semblance of life I've built could (and probably will) come crashing down around me at some point, and once again I'll fall behind.