Ready for a quick burst of cardio? This simple, classic exercise is something you can do anywhere, anytime, to get your heart rate up quickly — and it burns crazy amounts of calories [1]! Here's a quick refresher (and a reminder about form).

• Jump off the balls of your feet as you jump your legs out and then back in.
• Keep your core tight, back straight, and feet light. Move quickly!
• To modify, step the legs wide and then step them together instead of jumping.
• You can add a punch between each jumping jack for extra cardio. Perform for 45 seconds, then rest for 15 seconds.
• Add in some cross jacks [2] to work your inner thighs. Open your arms out to the sides as you jump your legs wide. Cross your feet as you jump your legs together while crossing your arms in front of your chest.