If I had a memory jar it would be full of things like...camping out at the river when I was little, cutting 4-wheeler trails with my cousins in the woods, riding the tractor with my Granddaddy, getting my first guitar, driving by myself when I was 16 and feeling so independent, meeting Robert at that tiny little church on a cold night, holding my sweet babies when they were so so tiny...and all of the wonderful things that are to come.
Maybe it's good that we can't hold on to our memories in a tangible form, like in a jar, because if we did, we would keep reliving those moments and not be open to our future and all that God has planned. Sometimes the good memories of the past are more comfortable than the unknown of the future.
But I hang on to Jeremiah 29:11: "For I know the plans I have for you,” declares the LORD, “plans to prosper you and not to harm you, plans to give you hope and a future." because this tells me that my future isn't exactly unknown. God knows it and has actually planned every detail of it, it may be unknown to me and that's fine because I know I'm not ready for what my future holds. I am not developed enough to be able to handle what God's going to have me doing 10 years from now.
So, because of Jeremiah 29:11, and so many other places in the Bible I can think of right now but I'll spare you the reading :), I can be ok with not having my special memories locked up in a jar waiting on me to come visit again. I know that what my future holds is worth moving on for.