Physical fitness results from two things, engaging in physical activity until muscles break down, and replenishing the body with healthy food and rest, especially sleep. As a result of this pattern, one’s muscles spring back a little bit stronger.

In similar fashion, intellectual vitality results from serious consideration of ideas that challenge one’s worldview. Instead of muscles breaking down, one’s assumptions do. Dan Dan the Transportation Man reminded me of this recently. DDTM is a good friend with whom I run about 25-30 miles a week. He’s the Federal Government’s boss man for Washington State’s freeways. Which means whenever anyone in our running posse gets stuck in traffic, we give him shit.

At the end of a recent run, he excitedly told me about a bold traffic experiment taking place in a small town in Northwest England. Here’s the introduction to the story:

No traffic lights. No traffic signs. No painted lines in the roadway. No curbs. And 26,000 vehicles passing every day through a traditional village center with busy pedestrian traffic.

It’s called “shared space.” Is it insanity, or the most rational way to create a pleasant place where drivers, cyclists, and people on foot all treat each other with respect?

The village of Poynton in the U.K. has undertaken one of the most ambitious experiments to date in this type of street design. . . .Variations on the shared-space model have been implemented in other European cities since the early 1990s, but never before at such a busy junction. Poynton’s city leaders sought the change because the historic hub of their quaint little town had become a grim and unwelcoming place.

After explaining the concept of “shared space”, Dan said, “It challenges everything I’ve always thought to be true about traffic planning.” Intrigued, he’s wondering whether some elements of the concept can be applied in Washington State. It speaks well of his intellect that he’s open to entirely new ways of thinking.

That sounds elementary, but it’s not. Increasingly, people surround themselves with like-minded people. We suffer from intense intellectual insecurities so birds of a political feather fly together. Conservative Republicans and Liberal Democrats read different periodicals and blogs, watch different cable television news programs, and listen to different radio stations. Then on the weekend they socialize with people whose politics affirm their own.

As a result, intellectual laziness prevails. It’s not nearly as obvious as our suspect physical health, but our intellectual well-being is just as bad. It’s impossible to maintain any kind of intellectual vitality in an echo chamber. We must exercise our minds by reading material and talking to people who we know see the world differently than us. For example, this weekend I read Peggy Noonan’s Wall Street Journal article titled “The Inconvenient Truth about Benghazi” (nearing 3,000 comments).

Many of my liberal friends wouldn’t read the article because it appears in Rupert Murdoch’s paper and they’ve disagreed with things Noonan’s written in the past. We write one another off, on both the left and the right, all the time. I’m guessing most of my liberal friends would give the Obama administration the benefit of the doubt regarding their initial explanation and believe the mainstream media already accurately reported the story. I found Noonan’s article well reasoned; cogent; and in the end, quite damning. My intellect is better for having considered her perspective.

Live differently. Test your assumptions and exercise your mind. Your intellectual vitality is at stake.