Burpee

Most people turn the burpee into a sloppy race and lose what makes it work: the plank position. Start standing. Drop down, place your hands on the floor, and shoot your legs back so you land in a solid plank — your body should be rigid from head to heels, core braced. Then jump your feet back in toward your hands and stand up. If you want to add a push-up or a jump, do it, but the real work is staying tight in that plank. Don't let your hips sag or pike up. Quality over speed.