Feeling jittery before a race is normal, but staying sharp is key. One handy...

https://xeon-wiki.win/index.php/How_to_Build_a_Pre-Performance_Routine_That_Actually_Sticks

Feeling jittery before a race is normal, but staying sharp is key. One handy trick is to breathe in for four counts, then out slowly for six to eight—this helps calm the nerves