I believe in my ability to recover. I'm an optimistic, cheerful and was (before CFS,) extremely energetic and active person. However my positive approach hasn't made a blind bit of difference to my symptoms. In fact it's made things more difficult due to constant frustration at my failure to make myself recover. For me, the ONLY thing that has helped is learning to accept that this is how I am today and that tomorrow will be better if I am rigorous about pacing myself today. From what I've read that's a common experience. Even NICE now recommends that CBT is only used to help patients to come to terms with the condition, rather than to help them recover from it. Because the latter has been shown to be ineffective and unhelpful.
There is some evidence that SSRIs help some people with CFS, but no-one knows for sure why that is. We also don't really know what causes CFS. There is a lot of speculation and some research has shown correlation between, for example, brain inflammation, mitochondrial dysfunction, various other conditions and CFS, but correlation is not the same as causation.
Neuroplasticity is indeed amazing and is particularly helpful with conditions that are purely neurological in origin, such as brain damage from injuries or illnesses, but it has it's limits. Otherwise all illnesses and and mental disabilities would be wiped out by the brain building new pathways with which to heal the body.
It's really unkind to tell people that recovery is possible of they only do x, y or z. That simply isn't true and it's rather difficult to 'get on with your life' when you don't even have the energy to sit up or (as that poor girl above), chew and swallow simple food.
ETA, maybe I missed them and I'd be delighted to be proven wrong, but I haven't seen any large scale, peer reviewed studies or reviews that have shown a clear cause of CFS, only many smaller ones that use 'suggest', 'indicate' or similar terms in their study conclusions.