Raise your hand if you want your park, or your job, or your favorite restaurant to be closer to where you live. The way to achieve this is to live more densely.
It's easy to imagine dense living as lack of personal space, as scary strangers, as expensive rent and a lack of peace and quiet. But it doesn't have to be this way. It could also mean more public space than one person could ever use, a vibrant community for every interest, less money spent on transportation and quieter vehicles that don't need the powerful (and noisy) engines required to travel long distances.
Imagine for a moment that we could take an entire metropolitan area and keep the population the same while doubling the density. We'd suddenly have hundreds of square miles of roads and suburban homes that could be reverted back into greenspace. And all of those millions spent on roads could instead be spent on education, other public services, or even lower taxes.