Unlike most grandparents of the past, your activities will be almost unlimited. Further, you will be there for your grandchildren not only through childhood, but you will be there for them through their teenage years, well able to serve as guide and mentor during this difficult and formative period.

Then, in twenty year's time, when they in turn have children, you will still be in sufficient good health and good shape, to do it all again with the great-grandchildren. You will still be sufficiently mobile to do a great many things with them, again teaching them and guiding them in a difficult and complicated world.

And where the parents may at times be too rushed or stressed, with your time, patience, and experience you may be better situated to help these future generations than anyone else.

In fact, helping them to unfurl their sails and gently puff them with wind, and helping them set the rudder so as to steer through the shoals, may turn out to be some of the more rewarding experiences of your life.

And when their children arrive, and you are perhaps a hundred or a hundred plus years of age, you will be there to welcome them, too - your great-great-grandchildren - into the world. By this time the more vigorous activities may be denied you, but you will -most of you - still be able to do a great many things with this generation as well.

Enjoying these future generations, serving as mentor and guide, may well come to be the focal point of your life. But you will, of course, keep up with other activities you enjoy as well - tennis, swimming, hiking, travel, golf, and so on. All of this goes without saying.

But there is another dimension to these years that may also come to play a significant part in your extended time on earth - at least for many of you. And it involves changes we have observed in a great many people as they come upon a certain age.