We go through different stages of life.
Even though our bodies may grow old as we aged but in mind we can still be young.
I always believe that we can be a part of our children's lives and do interesting stuff. Communication with the younger ones are important to be a part of old age. If we do not be active then everything may come as standstill... Then life might becomes meaningless.
So, as a part of growing old, what matters will be able to enjoy life together with the children and seeing them forming their own family.
The joy of witnessing the birth of their children and watching them growing up will be the last chapter of our lives.
That is the cycle of human lives.