Illustration copyright 2005 Nucleus Communications, Inc. All rights reserved. http://www.nucleusinc.com
Lie on your stomach on the floor with your arms straight out ahead of you. Raise your opposite arm and leg (for example, raise your right arm and left leg) a few inches off the floor and hold them there for 5 seconds. Lower them to the floor, and switch to the other arm and leg. Repeat 10 times.