Exactly. We don't need to exercise now, so few people do. Exercise has become something to do in our spare time. We stay in our homes and are required to use cars. When I visited China, I had to walk everywhere because I didn't have a car. Unfortunately we really can't get rid of the car obsession without a huge effort.

First, the suburbs take up so much space and distances living areas from the store areas. If we had a New Urbanist city, it would get people to walk. Now, you can't walk. Walking is impossible. You can't walk to a Walmart and grab fresh food every day. In China, my family would get food from the market every day. Now, we get food once a week and it's in big bags. That's because buying food is inconvenient.

Second, the suburbs take up space and creates the dreaded long commute. You can't walk to work. This makes public transportation unfeasible. Everyone buys a car.

It's all a big self-propelling problem. It creates its own problems, and to fix them, you have to contribute to the problem. Long distance? Get a car. A lot of cars? Build more roads. The vicious cycle continues...

EDIT: Biking is possible. But does anyone do it to commute, with so many cars and such long distances? Nope.

I personally witnessed this myself. I had to come home from school one day and today's roads aren't good for walkers. There's no sidewalk, so I had to walk on the grass or in the ditches. In many places (in the burbs, not in the city, the city is fine for walking), there were no walk signals. If there were, you had to walk along the road to the signal which often required adding more walking to the trip. For example, I had to cross the street from the library to a restaurant for lunch. I had to cross the middle of the road, and no one wants to do that.