Working helps us pay the bills, buy food, pay the mortgage and live as comfortably as we can.

But how we work though has changed significantly in the past 20 years.

While there are more jobs available, for the first time in many years full-time work has fallen while there has been a spike in part-time or casual jobs.

"Part-time jobs have been growing and we're now around two-fifths of jobs are part-time jobs, and three-fifths are full-time jobs," Patrick Fensham, urban planner with SGS Economics and Planning, said.

"There's uneven growth in terms of full-time jobs, there is more casualisation, people are not being able to access the more certain and full-time employment they're seeking, and we're seeing the manifestation of that in terms of stresses around household income."

According to data from SGS, there were 2.6 million jobs in greater Sydney in 2016 — 1.9 million were full-time and about 750,000 were part-time or casual.

In the past 10 years employment in Sydney has grown by 800,000 jobs, with most of that growth occurring in western Sydney.

The industries employing the most people are professional, scientific and technical services, followed by health care and social assistance.

We're more likely to end up working for ourselves or a contractor, says Professor Phillip O'Neill. ( Supplied: Start Up Stock Photos )

According to the Australian Bureau of Statistics, a growing number of people are juggling multiple jobs to meet the pressures of Sydney's living costs and housing unaffordability.

And for those that may need to work part-time for family reasons, Mr Fensham estimates that up to half of those people would like to work more.

"People would like to have more income to pay their bills and that's an increasing problem for our cities and our country, and there is effective underemployment and people are unable to get the work scope they'd like to," he said.

Young people struggle to find work

The hardest hit in our community in terms of job security are young people, according to Professor Phillip O'Neill, director of the Centre for Western Sydney at Western Sydney University.

"Since the global financial crisis there has been virtually no recovery in young persons' full-time employment whatsoever," he said.

"If you're a young kid in Sydney and you don't have any post-school qualifications, you're obliged to take a part-time or casual job or not work at all.

"The full-time labour market for an unskilled worker has disappeared in the Sydney labour market."

For 20-year-old Tyler, working in the construction industry is only temporary work until he can find something else.

"I work to live basically, and for my indulgences," he said.

"I love my job but it's not what I really want to do."

Retail and hospitality are supported by casual and part-time workers. ( AAP: Lukas Coch )

Michelle from Penrith told ABC Radio Sydney that casualisation of the workplace did not just affect younger generations, but also discriminated against older workers.

The 43-year-old has been looking for casual retail work as she and her husband are unemployed and receive support from Centrelink.

"Young people are getting all the casual and retail jobs because they are cheaper to pay," Michelle said.

"When I worked in retail in the past, the younger people got all the shifts and I only got work if they didn't turn up.

"It's very difficult. The work that is out there and hours that are out there is the same as what I'm getting from Centrelink, so there's no point getting a job for only 10 hours a week ... sometimes I think it's not worth it."

Professor O'Neill said that in an increasing culture of part-time and casual employment, workers were likely to be monitored more closely, be given fixed-term contracts and be more vulnerable to redundancy.

Concentrate on western Sydney

According to Professor O'Neill, the population in Western Sydney is predicted to grow up to 2.9 or three million by 2036.

The big jobs growth is in health, education and personal services. ( AAP )

He said the key for job security in Sydney was to focus on supporting that growing population with better infrastructure and employment hubs like the one established in Parramatta.

"At current job creation rates, we will barely supply two-thirds of those resident workers with jobs in western Sydney," he said.

"In 20 years' time, we're faced with a huge problem of moving probably close to half a million workers every day out of western Sydney and half a million to return in the afternoon unless we create giant jobs concentration in western Sydney to deal with that problem.

"In order to meet the demand in the growth of resident workers in western Sydney, the equation is this: Western Sydney needs the equivalent of one Barangaroo worth of jobs, that's 25,000 net additional jobs every 18 months."

ABC Radio Sydney is investigating Working Sydney in a week-long focus exploring how we work now and how we'll work in the future.