Recently I heard someone talk about an experience to which they'd looked forward for a long time. And now the experience was history already. And that person felt sad about it being over.
Anticipation is at least half the fun, isn't it? And all too soon, what we anticipated is over and done. It's common to feel some sadness about that. One of the lessons in that for me is to really savor that time of anticipation. Enjoy every minute of the dreaming and the planning.
In fact, enjoy every minute of the experience, too. And then savor the memories afterward. It's all great.
This brings to mind a quote from Dr. Seuss, "Don't cry because it's over; smile because it happened."
Sounds like good advice to me.