NO GYM membership? Noosa personal trainer Dmitri Simons won't take that as an excuse.

The Sunshine Coast trainer, who is also head trainer for fitness website Exercises.com.au, is on a mission to curb Australia's increasingly sedentary lifestyle with a series of exercises that can be done in a car.

The first video, "Seatbelt Flys", released last week shows Mr Simons demonstrating a common chest exercise known as "flys", using seatbelts for resistance.

The average Australian spends 39 hours per week sitting, according to the Australian Health Survey 2011-12, whether it's in the car, on public transport or during a typical workday.

Mr Simons said one of the best ways to counter the effects of long-term sitting was exercise.

"With so much information online these days, there's no excuse for people not to get started with a regular exercise routine", Mr Simons said.

Aside from the physical benefits of exercise, studies have shown it has positive effects on mental health.

"The body can influence the mind, and the mind can influence the body," Mr Simons said.