After Marine Corps Col. John Jansen, a pilot, had hip-replacement surgery, he wanted to find a challenging workout that would help him rehabilitate — and get him back into shape to fly again. But he also was concerned about being pushed too far and getting injured as he healed. On the recommendation of a colleague, Jansen started doing CrossFit — a strength and conditioning program — and realized he had found the workout that would meet all of his needs in a safe and efficient way. “Just over the past couple of weeks, I have found myself moving past the pain at a rate that I have not seen at all since the surgery,” Jansen says. “The instructor is extremely sensitive to my situation and my condition and tailors the exercises accordingly to really optimize the workout.” And that’s what CrossFit is all about, according to Jimi Letchford, chief branding officer. CrossFit, developed in the 1970s, is designed to provide a challenging and fun workout to members of the military and civilians alike. The reason why the workout is so effective, Letchford says, is because it’s based on three basic principles: constant variation, functional movements, and high intensity.