I don't really know. I can say with confidence that I cannot be consistent for months at a time. I've been in and out of the hospital every 6 months since 2018.
That is so stressful. A close relative has a similar situation. It is cyclical and is a condition that for some people does improve long term, so when she is on the upswing there is always the thought/hope that it might continue to improve. Then after a few months it goes the other way. Absolutely crushing. At this point, she has something akin to PTSD from battling through these cycles over the years. Hope you can find a sustainable groove.
Started a few years ago as a neuroimmune disorder with periodic and horrific OCD, depression, muscular failures, inability to concentrate, ... Much of that has passed, but it has morphed into ME/CFS. That still still seems triggered and/or related to an underlying neuroimmune issue. When the immune system kicks up, an autoimmune condition also ramps up and causes inflammation in the brain (among other things), which in turn leads to all sorts of symptoms. She used to run half marathons but now a flight of stairs are a big challenge.
None of it is well understood and there aren't good treatments. Some treatments help some people, but it is kind of hit or miss and most of the potential treatments aren't cheap.
It is actually similar in many ways to some forms of long covid, so bizarrely, covid and subsequent research may lead to better therapies that could help her as well. At least that's the hope...