Weird sadness before my long awaited trip which is already next week

I don't understand, why is that. So I am finally going on a big trip to Japan next week.

I've been working and working, waiting and waiting, hyping myself up for 2 years now, watching and learning about it. It's one of my biggest dreams and I was so excited, but... now that it's already right around the corner, I don't understand why I have this feeling of "sadnesss/depression", all of a sudden.

It's like the anticipation and awaitment is more exciting, or... when it'll be over, then what? That's so weird.

If anyone cared enough to read this, thank you. Does anyone relate?