A common CrossFit expression goes something like: “You don’t need harder workouts. You need to hit your workouts harder!”

This is a mantra that appeals to Brent Fikowski, who took second at this year’s CrossFit Games. “The more complicated and technical a workout becomes, the more opportunities there are to rest and hide,” Fikowski says. “Simple workouts are the most effective, and your effort will provide the results.”

If you want to wreck yourself quickly—we’re talking a full sweat, redlining heart rate, and aching muscles you can easily do in a lunch break—try any of the following CrossFit workouts.