Our Zen Teacher D.T. Suzuki once wrote,
We say, "In calmness there should be activity; ' in activity there should be calmness." Actually, they are the same thing; to say "calmness" or to say "activity" is just to express different interpretations of one fact. There is harmony in our activity, and where there is harmony there is calmness.
When we get out to, paddling into, and catch "big for me" waves, our minds really need to stay calm while we try to act one of the most active of the sport.