Take your right hand and gently rest your index and middle finger between your eyebrows. You will be using your ring finger to close the left nostril and your thumb to close your right nostril. To close the nostrils just apply minimal pressure to the sides of the bridge. This will be sufficient to block air flow.
Close your left nostril and inhale through the right nostril. Retain the breath momentarily as you block the right nostril with your thumb and open the left nostril. Now exhale through the left nostril. Your next inhale is through the left nostril. Again momentarily retain the breath as you close the left nostril and open the right one and then exhale through the right nostril.
This completes one round of nadi shodan pranayam (alternate nostril breathing). Repeat 4 or 5 times then lower your hand and breathe gently through both nostrils.
Breathe slowly and smoothly throughout this exercise and focus on the feeling of the breath as you bring it evenly to each of the three areas of body. Although deep your breath should not be forced or strained.
Because pranayam deeply rejuvenates the whole body, you will feel fresh and enlivened. You will notice how your mind slows down and becomes clearer and more focused and your body begins to release some of its tension.