This is one of the easiest breathing techniques that helps balance and calm us. Don't worry if your breath isn't equal when you begin. You can use this technique anytime. I sometimes tell students/clients to draw a little box if they're in class or in a meeting, and do some square breathing with the visualization of a box. It's simple:
1. Inhale & count to 4 counts (you set the pace to what feels right for you)
2. Hold for 4 counts (remember to work up to this, or shorten it, if it doesn't feel right for you)
3. Exhale for 4 counts
4. Hold for 4 counts (again, remember to adjust so it feels good for you)
The important thing is to try to get your inhales and exhales to be the same length. This will calm and balance your nervous system.