with your background, best option is for you to get a job in one of the big gyms as a personal trainer in central or admiralty or midlevels. the gyms in these area serve mainly high-flying financial guys who are all fluent in english. elsewhere in hong kong, they wont hire you for your lack of cantonese skills. for to get a job in one of these big gyms, you need a good qualification or certificate on sports ed or personal training...

plenty of people can teach english in hk. compared to a personal trainer, an english teacher doesn't get paid.