Pick a small object to be given one day to your great-grandchild. Write a letter to that child explaining why you have chosen this object.

This was the key to my Grandmother's house. That makes her your great-great-great-grandmother.
When my Grandmother died, my Mum had copies made of the key to her house and gave them on silver chains to me and my sister. I think of this key as a key to my past, my family and my heritage. Mostly it is a key to love.
Think of love when you see it and wear it. It's nice and heavy, so you'll be aware of its presence whenever you wear the chain around your neck.