When working with the inhale in Mahāmudrā try
to create an effect of upward movement in the spine,
as if within Bhujaṅgāsana inhaling from the top down,
whilst arching the spine upwards through the inhale.
So straightening the spine lifting the chest upwards,
whilst keeping the Jālandhara Bandha locked down.

Link to Series: 108 Mudrā Practice Pointers