Thanks for the feedback and that's interesting - I wonder if your free-diving training has something to do with it - I guess you must be very attuned to feelings of hyperventilation before a long dive? If it feels like you're hyperventilating, you could try turning down the breath volume (to low) and increasing the sensitivity (to high). The standard box and rectangle breathing are relatively short breath phases and holds - the Deluxe version unlocks all the visuals, gives more progress data and does include some much longer breath phases. I would like to add custom timings too, so people can set their own exercise.