If I get 3-4 hours in a day that I can function half way normally, then it's a good day.
Those days are not many.
I have to have physical therapy or my day is limited to an hour or two, if that. Without physical therapy the pain-fatigue cycle runs it's full route.
I'm supposed to do 3 sets of stretches at home each day. I can't do them the days I have physical therapy, for the PT, and the driving is more than enough to increase fatigue. On the days I don't have physical therapy (half the week) if I have to run any errand, that cuts at least one stretching set. If I have to use 3-4 hours doing something, including driving, then I can't do any stretches. (Not full sets)
It takes me 30 minutes to do the stretching at home, and an hour to two to recover. I can't maintain even with that as I'm not strong enough to do any real preventative work, thus the PT. I can't progress even with PT. (But I digress without the PT 3x a week.)
If I don't STOP and fully rest, and do self care... then the fatigue of the muscles causes extreme spasming, thus increasing the pain... if I push through any pain, then the fascia and the nerve signals really go haywire creating pain, and cause the muscles to spasm, thus increasing the pain.
If I become emotionally stressed and upset, that, too increases my pain and/or muscle response and more pain etc.
It can take two weeks to recover from an activity (say full day's) I've had recovery time of nearly a month for some flares not related to any particular activity.
I can usually determine ahead of time if an activity will be worth the result after the fact. Spending the full 4 hours (pushing when I'm not really up to it) will result in at least 2 full days of recovery time. (I'm talking full bed rest, ice packs etc)
What's also really tough is something like a grocery store trip. I have to use the go buggy... and what might take someone 30 min. to shop, takes me nearly 2 hours... due to decision making through the pain I'm always in. If I shop at a clothing store ...by the time I walk to the department and move hangars to browse... I often have to leave before viewing much, due to fatigue and pain.
I try to drag out to a restaurant for a meal each day (try to eat only half so I have that half for a meal at home later.)
I like your phrase "undoing your doing" and will use it IRL. TC