Founder of CrossFit Enurance, Brian MacKenzie, believes that short, intense exercise can give you many of the long-haul benefits of classic distance workouts—and spare you the chronic injuries and boredom. To try this 12-week program for runners, seek out a CrossFit endurance gym or coach (There are hundreds listed at CrossFitEndurance.com).

“If you can’t make it through the first week, back off a little,” MacKenzie says, then add reps as your strength and stamina improve. Your performance should get better each week.

CrossFit-style WODs are used throughout this program. To access them, go to outsideonline.com/WOD and select one of the duration indicated. You can choose any Wod, just avoid repeating a single one too often—the goal is to work different muscles each time.