TAKING a walk or getting frisky are Australia’s favourite forms of physical activity.

But when it comes to getting serious about exercise, motivation is the biggest hurdle for half of us, a survey has found.

Walking topped the list of ways to get in shape, followed by sex at No.2, using gym equipment and working out at home, according to the 12WBT fitness survey.

Celebrity trainer Michelle Bridges, co-founder of the online health and fitness program, said the turning point for most came when they jumped on the scales.

“Motivation is like a bad boyfriend - never there when you need it,’’ she said.

“People think they have to be motivated to exercise.

“We’re not motivated to wash our car, brush our teeth or put our clothes away but these are things we just get on with. People just need to turn up.’’

She said setting goals was helpful, as was finding an enjoyable way to exercise, whether it was netball, dancing or even the trapeze.

Recruiting a family member or friend to join also helps motivation.

“If the thought of going to the gym makes your stomach turn, look for things that don’t feel like formal exercise,’’ she said.

“Some might play cricket in the backyard, or go for a bike ride.”

Melbourne lawyer Kathryn Smith received a scare when a GP told her she was in the obese range, and has dropped 25kg in 18 months, even running a half-marathon.

“I can’t believe I got that far,’’ she said.

“Right now I’m pretty happy with how I look, my goals are more related to fitness.’’