Why run, walk or stand when you can sit? According to surveys, this is a motto for many of us. Typical adults sit for 9.3 hours each day - that's more than we spend sleeping (7.7 hours). For children, it's up to six hours. Sitting at work, sitting at school, sitting at home, sitting in our cars. Combined with decreasing levels of physical activity, the effects of our sedentary ways are catching up with us - and our waistlines.

According to the Australian Institute of Health and Welfare, three out of every five adults is either overweight or obese. For children, it is one in four. Nationally, obesity has overtaken smoking as the leading cause of premature death and illness in Australia. Globally, the number of obese people now outweighs the number of malnourished. And growing in partnership with our waistlines are associated medical problems like Type II diabetes, heart disease, high blood pressure and asthma.

Each year, we invest huge amounts of money towards new developments and infrastructure. Yet we spend almost nothing learning about how these built environments - new housing complexes, highways, playgrounds, streetscapes and parks - affect our health and habits. As urban designer Jan Gehl said in a recent interview, ''We definitely know more about good habitats for mountain gorillas, Siberian tigers, or panda bears than we do know about a good urban habitat for Homo sapiens.''

And it's not just our physical health which can benefit. Studies have shown how contact with nature can reduce anger, frustration and aggression; increase our sense of belonging and acceptance; and feel greater satisfaction with one's home, one's job and life in general.

Earlier this month, a new exhibition at the Gallery of Australian Design (www.gad.org.au) called BLOOM: Healthy Spaces Exhibition 2012 proposes we look at our world from a landscape perspective - where we live, where we work, how we travel - and assess how the design of these everyday spaces are keeping us healthy or making us sick.

The exhibition demonstrates a selection of projects which focuses on the contrasts of how we approach - and value - different types of outdoor spaces. Twenty-six projects are featured from across the country, grouped under the themes of Play, Work, Live, Heal, Travel and Learn. The work represents different types of spaces and a broad range of users, from a local town walk in a small mining town, to contending with issues of homelessness in a Sydney park, to better understanding how incorporating views and the outdoors in hospital design can promote healing.

The exhibition is the product of a Call for Projects advertised on the Australian Institute of Landscape Architects website, where design professionals were invited to submit built work which they thought addressed people's health and well-being. A total of 68 projects from across the country were submitted from 21 private design firms, six city councils and two health professionals.

An interesting aspect of the exhibition are the projects which weren't put forward by designers. For instance, not one housing development was submitted - a glaring gap, considering we spend such a large share of our lives in our homes. Also unmentioned are shopping centre upgrades, where sidewalks, seating, shade and lighting can transform such areas into thriving destinations - and whose absence can result in struggling businesses and graffiti dens. Sporting ovals are often viewed as important sources of recreation - yet again, none were included.

If such projects are not being put forward as promoting health, perhaps we should accept that their current standard of design is encouraging unhealthy patterns of use. Living in areas where we can't walk to parks. Shopfronts whose design accommodates the car, but not the pedestrian. Sporting ovals that allow the occasional cricket game (played by 2.1 per cent of the population), but are too exposed to engage a broader set of users for activities like walking (preferred by 36 per cent of the population).

The design profession needs to take more responsibility in assessing whether the behaviours we're shaping through our designs are encouraging healthy patterns of use, and identify which ones need changing. But in order to do this, we need to start being more proactive in gathering research about the impact of what we're building.

There are also real opportunities to increase contact and collaboration with those in public health, many of whom are already doing research into the impact our built environment has on people's health and behaviours.

With health issues like obesity on the rise, it's important that we start finding ways of prioritising people back into the way we design our spaces. Because it doesn't take long to determine when outdoor spaces were designed with people in mind, or included as an afterthought.

Gweneth Leigh is a freelance writer, landscape architect and curator of BLOOM: Healthy Spaces Exhibition 2012, which runs at at the Gallery of Australian Design until June 9.