Sitting at his desk at work, Oliver Shawyer would get so anxious he thought he was having a heart attack.

"I'd get uncontrollable perspiration, an increased heart rate and then horrible chest pain," the 30-year-old Sydney advertising executive said.

"The only way I could deal with it at the time was by inflicting pain to distract my mind. To stop myself from crying, I would just dig my fingers right into my legs".

Mr Shawyer is one of up to 2 million Australians who have anxiety, the most common mental health condition in the country.