Ninety seconds

Start by sitting in Half Lotus (Ardha Padmasana) or Thunderbolt pose (Vajrasana), ensuring that you have a stable base. 

Now extend your arms out and up at a 60-degree angle, with your elbows straight, creating a V shape with your arms.

Inhale. Initiating the movement from your armpits and keeping your elbows straight, exhale and cross your arms over your head, in front of your face.

Inhale and separate your arms into a V, then exhale and cross your arms again, alternating which arm is on the outside. 

Keep repeating the arm movements, inhaling as your arms spread apart and exhaling when they cross. 

The breathing style during this exercise is similar to what is called Kapalabhati in other traditions, with a sharp exhalation moving up and in from the navel, and a brief passive inhalation. 

Do this exercise for ninety seconds.