Planks
Come to a plank position as if you were going to do a push-up. Hold your body weight up with your hands faced down and lift your body with your toes. To make it more challenging, grab one of your hands and touch your shoulder. Alternate arms and repeat 10 times.
Mountain Climb
Come to a straight-arm plank position with your hands directly below your shoulders so that your body forms a straight line from your neck to your ankles. Then lift you right foot and bring your right knee up to the center of your body. Do this as many times as you can for 1 minute.
If you need more guidance, check out this 32 minute home cardio workout: