WASHINGTON — 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 today.

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.

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

Walking really countsRegular 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 goalsThe 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.

The reactionMillennials in particular are pushing for walkable communities, and Murthy’s call may help them work with officials to overcome policy barriers, like zoning laws.