When I do diaphragmatic breathing, I say to myself "Inhale 1,2,3" and
then "Exhale 1,2,3,4,5,6" slowly through pursed lips. . This helps my mind focus on correct breathing, and not on other thoughts that can cause anxiety and raise blood pressure. I use this technique when I experience arrhythmias.

The breathing should be gentle, relaxed, and not forced. Your diaphragm muscle will rise and fall. One therapist told me to imagine a baby lying on their back peacefully asleep. You will see the diaphragm muscle rise and fall in a gentle rhythm.

A pulmonologist told me years ago that I was a "chest breather" and breathing incorrectly . It took time to train my body to breathe correctly all the time.

I hope everything goes well with your exam. Keep up the positive lifestyle changes!