Any Tips please

Hi,  Im a high functioning adult with ASC,  my hobbies surround sport.  I've recently started expanding the competitions I compete in to a higher level but really finding my brain as a blocker . I am so focused on feeling out of place as though I don't belong and being embarrassed rather than concentrating on what Im supposed to be doing.  I also struggle with this in work ,  I'm more worried about what people will be thinking of me even though i know they don't care.   

Anyone got any advice or tips to help out.