Isn't it ironic. When you most need to think clearly you are least able to.
My classic one is when I overheat. Because of my POTS my fatigue builds rapidly when I'm too warm, as does brain fog. The brain fog means I don't realise I'm too hot, nor that I should do something about it. I wondering why I feel worse and worse until I crumple into a flollopy mess, where I stay. Unable to work out how to improve things. Until someone asks me why I'm wearing a jumper (called a "sweater" in American) or tells me to put my cooling vest on (or something similar). Or I have a flash of inspiration that makes it through the fog. I've lost entire days to hideous fatigue and brain fog just because I was wearing a jumper . Pre-diagnosis, and in the first few years post diagnosis I probably flolloped for whole weeks because of this.
Now I have pre-arranged recovery plans.
When fog starts to build more than expected, take jumper/blanket off, pop outside/somewhere cold to see if it helps.
Move. See if getting the blood moving helps.
And if these don't work I switch to 'recovery plan' (some people also call it a 'Flare-up plan'
Lie down. Properly. So head is level with or below the level of my heart (again, this is a POTS management tool - getting the blood and oxygen back to the brain).
And switch to 'light duties' only, no big concentration, favourite music/DVD, bits of colouring/jigsaws, frequent short stretching & gentle movement, no vigorous exercise, minimal food prep, Eat food my body finds easy to digest (carrots, tuna, eggs, crisps, well cooked greens, soup), make sure joints are supported and not flopped to end of range.
This routine helps me get back on track. I might have tasks I have to complete - but then I return to this routine until the fatigue lifts back to normal levels. Recovery is a lot quicker when I follow this plan. Even quicker than it does if I simply curl up on the sofa and don't move all day (periods of sofa time are fine, but my body does better with lots of small bits of gentle movement). Because it's kinda 'established' I don't have to work it out. True, I still need to realise I feel awful, but having the plan literally written down and stuck somewhere obvious (like on the fridge) can be a real help. As can letting people around you know the plan and asking them to remind you if needed. Even people who are 'around' on line can help - I've lost count of the number of times I've been text-chatting, and the person I've been chatting to has noticed my typing accuracy and coherence decreasing, and have asked "Are you wearing a jumper?" :D If my clarity of thought has been stolen by fatigue, using someone else's seems a really good idea!
(the specifics are what works for me - everyone will have different specifics, but having an emergency plan is something I'd strongly recommend to anyone with a fatigue-causing condition)
But what I love doing (and need to do more) is the 'cunning plan'.
pacing magnets), complete with phone alarms and desk alarms for: swapping activity (see 'swap don't stop' blog post), meals, rest periods, snacks etc.
And writing down my To Do list in sections of easy/OK/challenging - and mixing it all up throughout the day so I don't overload with challenging and drain my precious energy too quickly - shifting things to tomorrow if I realise it's not realistic to do it today.
I get so much more done on these 'cunning plan' days - and I feel so much better at the end. Fatigue won't stop the sensible decisions because I've already done the main thinking AND the cunning plan also reduces the level of fatigue that I get. Win-win!
Of course, unavoidable things happen. Illness, flooded kitchens, social events. If we know in advance it's worth putting a cunning plan into place to minimise the fatigue (I always do cunning plans for big social events, with things like where and when I can sneak out for a lie down, I take snacks, stick to easy-digest food, take my cooling vest and wear it if other people take their jumpers off.)
And the unexpected stuff that totally steals the plan and the brain? Well, don't beat yourself up. It happens to us all - the recovery plan is there to help pick up the pieces without needing lots of brain.