This old-school exercise offers a real-time assessment of your strength and motivates you to improve your fitness.

Push-ups have long been the symbol of optimal fitness. They are still used by the U.S. Army and the Presidential Physical Fitness Challenge to assess strength and endurance.

For older men, the simple push-up can be used as a snapshot of their current fitness. "Push-ups are the classic bread-and-butter exercise,"  "How many you can do at one time offers a measurement of your strength and is an easy tool to help you improve. You can do them anywhere and at any time, and only need a few minutes."