4) Jumping Jacks
How to: Bend your knees and jump, moving your feet apart until they are wider than your shoulders. At the same time, raise your arms over your head. You should be on the balls of your feet. Then jump again, bringing your feet together and your arms back to your sides. Keep your abs tight throughout the exercise. If you want to add difficulty, lower into a squat each time you jump out.
Why: Jumping jacks work your shoulders, back, thighs and calves. They are easy, can be done anywhere and are also good for your heart.