“It’s not that the cream has risen to the top and the cream is 100 percent male or 80 percent male,” Susan Hennessey, a national-security expert who organized the Brookings list, told me. “We’re failing to capture talent that exists.”

All of which means that journalists aren’t being neutral if they just go about their business and pretend to ignore gender. They are allowing sexism to help dictate their sources — and are perpetuating the problem. The people who get quoted today, after all, are more likely to be invited onto a panel tomorrow and offered a sweet new job next year.

I have long felt a little lousy about the gender mix in my own work. But I’ve made the usual excuses to myself: Many of the subjects I cover, like politics and economics, are dominated by men.

When I began writing a daily email newsletter in 2016, however, I decided to try something new. The newsletter includes a few paragraphs that I write about the news, as well as some reading suggestions from around the web. And I made a simple rule: No newsletter can cite the work of only one gender. Every newsletter has to be coed.

The rule has changed my work. Without it, I would too often rely on familiar voices, most of which are male. Because of the rule, I have gone looking for a wider variety of experts. That’s not merely a matter of fairness. It broadens my worldview and improves my journalism.

In recent months, more than 40 percent of the writers mentioned in the newsletter have been women. By comparison, less than 20 percent of the people mentioned in my weekly column have been women. The gap between the two is a pretty good demonstration of the difference between vaguely wanting to get better at something and having a plan to do so. As LaFrance said to me, about her own work: “Caring is not enough. You have to figure out how to do something about it.”