The 4-7-8 breathing technique, also known as “relaxing breath,” involves breathing in for 4 seconds, holding the breath for 7 seconds, and exhaling for 8 seconds.

These types of mindful breathing exercises have been shown to have many benefits for stress reduction and relaxation. It also helps reduces anxiety and calms the nerves.

Why an extension? 
We spend a lot of time on our computers, especially using a browser. Every time you open a new tab, you'll be reminded of this exercise, and because it's so conveniently placed, you might do this more often. The aim is to get you to incorporate this breathing exercise into your daily routine, even if this means just taking about a minute every hour or so. 

If you see benefit from this app, please give it a shout out on Twitter and use #478breathingapp. 

Disclaimer
Having said all of the above, I must not that this software is provided as-is. This is not a health app designed by medical professionals, but an open source solution developed by an individual trying to provide some value. If you have any doubt, please CONSULT YOUR DOCTOR BEFORE DOING THIS EXERCISE.