(CNN) Stanley McChrystal, a retired four-star general in the Army, says the ban on transgender people serving in the military is a mistake.

"I think it's a mistake to lose that talent ... somebody with those attributes, the willingness and the capability to serve, not being welcome, is a negative message to send," McChrystal told David Axelrod on The Axe Files , a podcast from the University of Chicago Institute of Politics and CNN.

From leading the Joint Special Operations Command and NATO forces during the war in Afghanistan to researching the qualities of successful leaders, highlighted in his book, "Leaders: Myth and Reality," McChrystal knows a lot about the common principles of leadership.

Spoiler: He says there aren't any.

Here are three leadership myths McChrystal debunked:

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