This sequence of exercises can give you a great workout in only 20 minutes!

1. Push-ups: On toes, knees, or any variation.  20 reps
2. Knee-ups: Stand and quickly alternate lifting right and left knee to hip height.  Do as many as you can in 1 minute
3. Goal post press: extend arms out to sides at shoulder height, elbows bent at 90°, palms forward.  Raise arms over head, then lower.  30 reps
4. Jumping jacks: 30 reps
5. Upper bells: Stand with feet shoulder-width apart, knees slightly bent. Place fingers behind your head and bring right elbow toward right hip, then left elbow toward left hip. 25 reps per side
6. Jab/cross: Stand with feet shoulder-width apart, left foot forward, knees slightly bent. Jab forward with left fist, then cross over with right fist. Do as many as possible in 1 minute. Switch sides for the second circuit.
7. Planks with Cross-Overs: Begin in full push-up position. Pull right knee toward left elbow, keeping abs tight and back flat; return to start and repeat, alternating sides. 15 reps per side

Source: www.fitnessmagazine.com