The way we experience life is a reflection of who we are.
How is it that two people can watch the same football game and one be extremely happy with the result while the other one seems utterly devastated? It all depends on our perspective. The event itself can not be the cause otherwise there would only be one reaction. It is our choice to cheer for one team or the other that creates the response to the event, or perhaps our choice to root for neither team at all!
The point is, if you take time to reflect on your life and how you react to every day situations, you will find that how you perceive events is simply a reflection of your perspective. By identifying what expectation you have that has caused your reaction, you can decide if you should change that expectation or not, thus creating a different reflection!
Some expectations are good and help you establish a set of values that you live by, while others just prevent yourself from enjoying the ebbs and flows of life as they come and go like the tide. Our lives will not always be cheery and happy so learn to let the little things slide and just enjoy the ride!