In fact, some of the physical and mental symptoms that are associated with getting older are actually due to the inactivity that so often accompanies aging, says Meena Garg, MD, of Indiana University's Center for Sports Medicine.

  To help ward off physical conditions that make it more difficult to stay active, such as osteoporosis, heart disease, and weight gain, you must get some type of exercise on a regular basis.
  Physical activity also helps you stay motivated by improving your mood and protecting against cognitive decline and depression. Here's what you can do to help yourself stay as active as possible.

 Maintain Physical Strength
  You may not be able to do strenuous exercise, but doing some form of aerobic or cardiovascular activity such as brisk walking, riding a bicycle, or swimming and also some sort of strength training with light weights, on a regular basis, will help you maintain or recover muscle mass, and give you the strength and coordination you need to stay active and reduce your risk of injury.
 If you have not been doing any formal exercise, and wish to start, speak with your doctor or a certified trainer first, to make sure you know which exercises are safest and most effective for you at this stage of your life.

 Be Flexible
  To be physically active, your muscles have to be flexible. Stretching exercises help ensure that your muscles stay as elastic as possible. Sign up for a stretching class or try yoga or tai chi, which can also help maintain or improve balance.
  Or pick up an exercise DVD that features stretches and is designed for older men and women to do simple stretches at home. Remember to warm up your muscles before you stretch. A few minutes of running in place or walking while pumping your arms can provide a good warm-up.