Gil Fronsdal leads an Anapanasati Breath and Peripheral Awareness. Taking an upright alert posture. There's a connection between posture & alertness.
And posture and relaxedness. To have a balance which expresses some modicum of alertness especially in the spine. To have a balance of feeling at ease in the body especially the shoulders.
Perhaps taking a few long gently slow breaths, to establish a connection with your body and with your breathing. Taking these deeper breaths is a way of letting the body know that here, this time, in this body, in this mind.
Then returning to normal breathing, just let the breathing take care of itself.
You might scan your body to see if there are areas that needed to relax.. the eyes, jaw.