Racing nerves can mess with your focus, but simple breathing really helps. Try...

https://future-wiki.win/index.php/What_Does_It_Mean_to_Treat_Arousal_as_Fuel%3F

Racing nerves can mess with your focus, but simple breathing really helps. Try breathing in for a steady count of four, then slowly out for six to eight. It calms your mind and slows the heart rate