This is key. Many years ago, I learned while reading Julian Simon's Good Mood that happiness is basically the ratio between your reality and your expectations.

This is key. Many years ago, I learned while reading Julian Simon's Good Mood that happiness is basically the ratio between your reality and your expectations. When your reality is immutable, adjusting your expectations is the path to happiness. I've had great results applying this principle to day to day annoyances. For example, when I go to meet someone, I always expect a 5-10 minute delay and go prepared (e.g. with a book). My loss (time) is the same, but my mood remains mostly unaffected. What's more, if the person show's up on time, it's a pleasant surprise.