I think these words work nicely in organ practice as well.
The mind is like a piece of steel - immovable and unshaken to whatever comes up during our practice or performance. The body - on the contrary - is so smooth, so subtle that every movement of our fingers and feet are quick, economic, barely noticeable.
And like any activity, organ practice can be a meditation. But only if you completely focus your mind on the current measure you're playing, breath deeply and slowly.
Inhale the positive, exhale the negative.
PS Meditation is yet another word for prayer, of course.