Prāṇāyāma is the practice of breath control in yoga. In modern yoga as exercise, it consists of synchronising the breath with movements between asanas, but is also a distinct breathing exercise on its own, usually practised after asanas.
You can do it anytime, anywhere. Breathing through your nose, observe the inhalation and exhalation. Which happens faster? Which is longer? Don’t manipulate them. Just watch. Continue for 2–3 minutes.
You can do it to focus your attention on your breath during asana practice. Inhale through your nose, then open your mouth and exhale slowly, making a “HA” sound. Try this a few times, then close your mouth, keeping the back of your throat in the same shape you used to make the “HA,” as you exhale through the nose.
You can do it at the end of an asana sequence to prepare the mind for meditation. Take a comfortable seated position. Close your right hand in a gentle fist in front of your nose, then extend your thumb and ring finger. Gently close your right nostril with your thumb. Inhale through your left nostril, then close it with your ring finger. Open your right nostril and exhale slowly through it. Inhale through the right nostril then close it. Open your left nostril and exhale slowly through it. That completes one cycle. Repeat 3–5 times.
You can do it after asana to prepare for meditation. Inhale, inflating the lungs as fully as possible. Hold the breath for 10 seconds. After 10 seconds, inhale a little more. Then hold it for as long as you can. One caveat: For anxious people, breath retention can be difficult. Stromsuggests starting with holding the breath for 3 seconds, or as long as feels comfortable, and working your way up.
You can do it to jump-start your asana practice when you feel lethargic or for brainpower when you’re foggy. To start, take a full, deep inhalation and exhale slowly. Inhale again, and begin exhaling by quickly pulling in the lower abs to force air out in short spurts. Your inhalation will be passive between each active, quick exhalation. Continue for 25–30 exhalations.