[bikeformind]

You might want to explore using haptic feedback via the devices vibrator motor to prompt the user to breathe in and out.

One short pulse for breathe in, and a longer pulse to breathe out.

This would allow the user to perform the exercises with their eyes closed and the phone on their lap.

I know the visual functionality is core to your design, but might be a good idea to provide some optionality for users who just want to do the exercises without looking at their phone.

[selfportrait]

+1 to this suggestion. It’s part of what makes the breathe app on the Apple Watch engaging, the stream of tapping on your wrist really helps. I’m sure the same can be achieved with the phone.

[llagerlof]

Also it will allow people with impaired vision use the app.

[lukko]

+1. I did add very subtle haptics (possibly too subtle) as the indicator changes, but I like the idea of making them stronger and recognisable for each breath phase

[bikeformind]

pick up a cheap Fitbit on Amazon, they have a pretty good haptic breathwork flow.

another interesting thought, maybe user could lay down on their back place iPhone on chest, and you can measure breathing with accelerometer? that could be even more accurate than camera + mic