The U.S. Army Ranger School has been in the news after enrolling its first-ever group of women. The trial enrollment has drawn sharp opinions on both sides, but it’s also highlighted the rigors of what’s been called one of the world’s toughest and best leadership programs.

If you think your MBA school or corporate training was hard, imagine a program where only about half of those who enroll go on to graduate, and a third of those do so only after repeating all or part of the course.