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Cities house over 60 percent of the American population while taking up just 3.5 percent of the national land mass. You don’t need to be an urbanist to know that’s called density. But it might help to be an urbanist if you’re going to figure out how to make it so cities don’t crush the souls of the people living in them.

Thus, the necessity of the work of Layla McCay, founder of the Center for Urban Design and Mental Health. McCay recently spoke with CityLab about how mental well-being can be designed into the very structure of the urban environment, and she highlighted four kinds of spaces needed for people to feel good about where they live.

Let’s take them in order.

You need “green space.”

Green spaces, formerly known as parks, have a multitude of psychological benefits. Spending time in nature has been shown to reduce stress and criminal behavior, restore attention, and increase people’s self-reported health. “This means space that you don’t have to make a special trip to, but space that you encounter in daily life — even green space that you see from your window,” McCay says. Much of the same holds for “blue spaces,” or ocean views. If you want to be more deliberate about getting your nature in, consider the Japanese practice of shinrin yoku, or wilderness bathing.

You need “active space.”

“When people are designing for health, this is the focus,” McCay says. “It’s a big opportunity for physical health, but there’s also a strong mental health correlation.” As in: Tons of research points to how physiological health drives emotional well-being, including a million-person study that came out last month saying that cardio protects you from depression. From an urban-design perspective, it’s not just parks that contribute to that, but active commutes, like walking and cycling — which are, coincidentally, the most energizing ways to get to work.

You need “social space.”

These are places where neighbors might spontaneously interact. “It’s a question of making public places more social, by, say, putting in more benches or setting up chessboards in a park or square,” McCay says. A bonus: It also reduces the need of going to bars.

Providing spaces for bonding looks increasingly essential: Several decades of research point to how social support bolsters well-being and makes people more resilient; and a clever study of getting strangers to talk on commutes indicates that people are more eagerly open than they assume, even for introverts.

And “safe space,” too.

“This is crucial, whether it means security in terms of crime, traffic, or, for people with dementia, safety from getting lost,” McCay says. “But you don’t want to design a safe space so that it feels suffocating or sterile. For example, people should have choices about which route to take rather than being constrained into one specific ‘safe’ route.” These things have cascading consequences, as illustrated by a 2016 study of single working moms participating in an education program in Philadelphia. Women living in insecure neighborhoods didn’t feel safe letting their kids play outside, so they stayed in the home — making it harder to get their own schoolwork done.