We, or at least I, tend to forget.
So that means that if I am going to share with my kids in a way that they can remember and share with theirs, I have to figure out a way to remember what God has done. Globally, that means that at least I need to be consistently in the Word. That will remind me of the overall plan of redemption, and what He has done to provide that for us.
But He has also done much for me. There have been prayers that have been answered, victories won, and challenges overcome all through His grace.
The only way I know to remember those is to write them down in my journals. Otherwise, I forget. So my journals become the means for me to share the majesty and power of God with my kids.