Test your breath retention time

Breathe normally and exhale.
Take a few normal breaths and then exhale fully.

Hold your breath and time it.
Hold your breath after exhaling and track how long it takes until you need to breathe again.

Breathe deeply 30 times.
Take 30 deep breaths, letting the air go on the exhale, just as you do with the basic breathing exercise.

Repeat the test.
Repeat the breath hold test again. You will find that you can hold your breath for significantly longer.