Today the average duration of human life in the United States is just about 70 years for women and a little less for men. Conservative experts believe that man is really build to last about 100 years; and that medial advances and more healthful living habits could bring this about within a generation or two.

What good is it to add years to life if we do not also add life to years? In fact, unless people learn to enjoy life and to grow old gracefully, the extra years may be an additional burden. From 18 to 30 years is roughly the period of highest physical and mental vigor.

The experiences we accumulate from the day we are born help us to conserve and to use our physical and mental abilities more wisely, so that for some time after 30 years we are able to perform increasingly well in spite of slowly slipping vigor. After age 50 the increasing accumulation of experience is no longer able to offset the now more rapidly energy and therefore aging begins to assert itself noticeably and in many ways.

A number of things may come about gradually such as people who have not used eyeglasses before may at some time in their forties need them for reading, and in the fifties they usually need bifocals.

Also in the forties, people are likely to put on weight because there is a general slowdown in the oxidation rate of the aging body tissue. Also we tend to do less strenuous work with no reduction in the amount of food consumed. And in the fifties there is likely to be some loss of hearing. Usually the high-pitched tomes go first, so words with the sounds of F, S, and TH are confused. A hearing aid may be needed in some cases.

Aging is generally accompanied by a loss in physical and mental flexibility. This is noticed in a tendency to become stiff in the joints; in slower comeback after a strenuous trip, excessive "night life," or hard work; in slower healing of wounds, sore muscles, and sprains; in slower recovery of pep after an illness; and in greater difficulty to adjust to new people, new places, and new ideas.

Men, especially, will notice loss of muscular strength. There will be increased unsteadiness and delicate muscle movements will be more clumsy and the stride in waking will become shorter. The conclusion now is that the performance and ability of the elderly has long been underestimated and can be greatly improved by a proper diet, sleep and exercise along with rest and relaxation.

Many elderly people tend to lose their joy and will to live and chronic worriers may mope around and withdraw. Medical authorities now say that laughter is one of the best medicines for the elderly. You can always keep your sense of humor tuned up by surrounding yourself with pleasant and interesting people. Just act your age and don't be afraid to laugh at yourself even when no else is around.

Now that we all know the role that physical activity plays in our lives, remember to do something physical every day. The joints must be used or quite simply they will tighten with age creating that stooped worn out appearance we so often associate with getting old. Keep yourself flexible and fit on an exercise program consistent with your ability.