By LAURAN NEERGAARD, AP Medical Writer

WASHINGTON (AP) — Take a walk: That's the U.S. surgeon general's prescription for sedentary Americans — but communities will have to step up, too, and make neighborhoods easier and safer for foot traffic.

Only half of adults and just over a quarter of high school students get the amount of physical activity recommended for good health, Surgeon General Vivek Murthy said in a "call to action" being issued Wednesday.

No worries if you can't join a gym or run a 10K. Walking is a simple, affordable way to get the needed exercise, Murthy said — if people have a place to do it.

"I firmly believe that everybody in America needs a safe place to walk or to wheelchair roll," Murthy said in an interview, urging a range of groups to work together to create walkable communities. "For too many of our communities, that is not the reality right now."

Some things to know about the surgeon general's walking campaign:

WALKING REALLY COUNTS

Regular physical activity reduces the risk of heart disease, diabetes, obesity and a list of other health problems — and can ease symptoms and improve quality of life for people already living with chronic diseases.

Guidelines issued in 2008 recommend that adults get at least 2½ hours a week of moderately intense physical activity. Children should be active at least 60 minutes every day.

To get your heart rate up, Murthy says walking should be brisk enough that you can still talk but not sing.

THE BARRIERS

People often say there's no time in their busy days to exercise, and their environment can make it harder to fit activity into everyday routine.

In many places, schools, restaurants and shops are located too far from home for people to walk. Busy streets may lack sidewalks, or there may not be adequate time to cross multiple lanes of traffic. Parents who live near schools still often cite traffic danger.

Neighborhood crime may be a factor in deterring walks. Older adults may fear falls.

THE GOALS

The surgeon general wants communities to make it easier and safer for people of all ages and abilities to walk where they live, learn, work and play — and to encourage them to get moving.

That will require efforts from transportation officials and city planners, parks and schools, businesses and health officials, and the public, his report makes clear. Options range from zoning decisions and building sidewalks, to promoting worksite activity. Murthy, for example, likes to hold some meetings while taking a walk.

Wednesday's report comes after Transportation Secretary Anthony Foxx last year began a "safer people, safer streets" initiative to help communities create safer walking and bicycling networks.

THE REACTION

Millenials in particular are pushing for walkable communities, and Murthy's call may help them work with local and regional officials to overcome policy barriers, like zoning laws, said Scott Bricker, executive director of America Walks, a nonprofit network of health and other organizations that pushed for the move.

"This is an official recognition from our nation's doctor that this is a critical health issue that needs to be addressed," Bricker said.