I've really been working hard at doing a better job of letting go of my expectations and being better on just letting things happen (and enjoying them as they do.) It's been a tough job for me as I'm definitely someone who tends to over-analyze things. Any time I'm going into a new situation where I have any kind of anxiety or anticipation, I spend way too much time thinking about it ahead of time. Thinking out every potential scenario and every possible outcome. Even rehearsing conversations in my head. Focusing too much on how I want things to turn out, and how I can nudge them in that direction.
Ultimately, this only leads me pretty consistently to disappointment. Things generally never turn out exactly how you want them, and I've invested so much time into working out every step of the process that, inevitably, at least some of those steps will come out differently and lead to a letdown of some kind. So much better, I think, to just go into the situation with no preset expectations. Let things happen as they will, and enjoy the outcome. No matter what it is.
The first step is recognizing when I'm engaging in too much rumination. And, for me, that's fairly often. I do it a lot. I'm getting better at rolling with the situation as well, and not letting any divergence from my expectations bother me as much, but I really need to learn to not build those expectations so much to begin with. It's a tough path, but I've at least started walking down it.