Hollow or empty the chest.
Round the back.
Something to note here...
With practices like this, typically, we aren't "trying" to "do" something.
As in with FORCE.
We want to let it happen.
Release the tension.
"Song" is the Chinese term.
These are more qualities or feelings we are looking for,
Rather than actions to make happen.
From Taiji Zen with DDR.
ENJOY. 🙏