Disclosure up front: I make Autonomic, a private HRV and symptom journal, and this is our biggest update yet. I am posting because pacing by feel kept failing me in exactly the way it fails a lot of people here: good morning, do a bit too much, fine all day, flattened a day or two later.

So we built the thing I wanted. Each morning your HRV, resting heart rate and sleep, compared against your own baseline, set a budget for the day in minutes of effort. It spends down as you go: logged activity, steps, time upright (which matters a lot if you have POTS), and minutes with your heart rate above your own line. Legs up and breathwork buy some back. A marker on the bar shows where an even day would be by now, so "2 hours left" means something different at 9am than at 6pm.

The parts I think matter most for PEM:

* It grades every under-budget day against the next TWO days, not just tomorrow, and shows you how often it has actually held.
* If it sees you heading into a downturn, it shows no number at all instead of a small one.
* Its ceiling only goes down when a dip gives it a reason, so a quiet week where your phone saw nothing does not shrink it.
* Optional alerts with the app closed (heart rate above your line for a while, nearly out of budget, ran over yesterday). Max three a day.

It is on iPhone and Android, with widgets and an Apple Watch view. Nothing leaves your phone. Pacing is part of Pro, but every install gets 14 days of Pro and pacing has its own free week, so you can see what it makes of your own days first.

Not medical advice, and it is not a prescribed limit. I would genuinely like to hear from people who try it, especially where it gets your days wrong. 

Introducing the Pacing Budget: Know How Much Today Can Take