compartmentalize...know that when the bell rings nothing else exists except your opponent and your corner...
first time I grappled in a tournament, I walked onto the mat, did that Diego Sanchez yoga inhale/exhale thin with hands over my face and closed my eyes. The referee said commence, I opened my eyes walked over and focused 100% on my opponent....I won in 40 seconds via a modified nogi Ezekiel choke from the mount
