Great read Niklas Göke! I totally agree. The main difference is that miserable people are reactive about their life and happy people are proactive. They make what they can out of every situation. And my mum always says, “health is wealth” — similar to your German one but different :-) And I just thought of this Marcus Aurelius quote to summarize the mood —

“You have power over your mind — not outside events. Realize this, and you will find strength.”

:-)