Begin by standing with your feet together, arms fully extended with your hands at your sides. Bend your knees slightly and push through the balls of your feet while straightening your knees in one motion. Quickly jump up spreading your legs wider than hip-width apart. As you jump up, raise both arms out and up in a smooth motion until your hands meet above your head. As you return to the ground, bring your feet back together and your hands back to your sides with your arms fully extended. Completing as many reps as possible in 40 seconds.
Image Credits: Jumping jacks