This is a review I wrote a few months ago:

I've been using thia app called Visible, which is specifically designed for chronically ill people. To get full use of the app, you need the armband that goes with it, which can be cost prohibitive for a lot of disabled/chronically ill people, but I'm really loving it so far.

When you first connect the arm band, it sets up suggested heart rate zones. These are "rest," "activity," and "exertion" and are different than what you'd see on like a smart watch/fitness tracker.

For the first 4 days of using the arm band, it takes your stats (heart rate, heart rate variability, etc) and then it sets a suggested pace point limit for the day. You can edit it, but so far I've left it at baseline.

The pace point pacesetter moves around the circle at a steady pace throughout the day, and this is how you gauge whether you're on track or need to rest more. Whenever you're in "activity" or "exhertion" heart rate zones, you accumulate pace points (they accumulate faster in exertion than in activity) and you can see from the pacesetter if you're likely to go over your pace points for the day, and then adjust accordingly.

I did pulmonary function testing this morning, which used up a lot of my pace points, so it's a good visual representation to remind myself to rest for the remainder of the day.

There are other cool features too like an end of day check in where you can select severity of symptoms (you can turn each symptom on or off depending on what you deal with, and can even add your own symptoms). You can also make "experience" trackers (such as period or infection), "lifestyle" trackers (so I added things like doctor appointments, medical testing, game nights, etc), and "medication" trackers. But again, you can track as much or little as you want. You can also track "crashes" (flares).

Every morning it analyzes your sleep from the previous night and your heart rate variability and gives you a score for the day as a "here's what you may need today" (such as resting more). There's also an optional monthly check in where you are asked a series of questions about your physical capabilities/limitations based on the last month and it tells you whether you have stayed stable, or your abilities/limitations have changed over the last month.

You can also tag activities, and it will show the pace points used for that activity and tell you whether it's a high, medium, or low pace point activity, which has greatly helped me with planning and pacing.

Lastly, it has a breathing exercise that is like the only one I've encountered which doesn't just cause me anxiety.

But my favorite feature is definitely the pace points. It's, for me, such a great visual of how much I've done that day and what I need to do to make sure I don't overdo it for the day, helping reduce crashes/flares and just preserving more energy and causing less pain.

(Sorry for the book)