When you buy through links on our articles, Future and its syndication partners may earn a commission. Credit: Getty Images A sweaty, rewarding workout session isn’t guaranteed, it’s earned — usually.

We all want simple workouts that deliver results, and that's why the 21-15-9 format has become a staple in high-intensity functional fitness. Originally a CrossFit workout, it involves completing one ...

When CrossFit workouts are at their best, they challenge your mind as much as your muscles. They push you to grind out rep after rep, battle fatigue, and utilize fitness tactics-and they very often ...