The Mosman Park resident received his black belt last month.
Mr Pettitt, a retired boilermaker, has been training with the ATI Martial Arts School in Claremont for three years, and director Gary Newman said he was an inspiration.
‘Michael trains up to five times a week,’ Mr Newman said.
‘He is very dedicated and has shown massive improvements.’
Mr Newman said that after his pupil was told by another martial art school that he would never be a black belt, he refused to be deterred.
‘This man is a trooper and I am inspired by his will and dedication,’ Newman said.
Mr Newman said Mr Pettitt had become a role model, not only inspiring young athletes but also parents and older people who were motivated to learn and enjoy the sport.