Introduce your elbow to your knee when you introduce this exercise to your day. It makes for a quick and easy full-body workout. Just start on your hands and knees with your wrists directly under your shoulders and your knees directly under your hips. Reach your left arm straight out in front of you and your right leg straight back. Then, bend your arm and leg, bringing them into your body until your elbow touches your knee. Repeat with the other arm and leg.

Adults need 30 minutes of physical activity every day. Kids need 60.