How to make a great decade?

Apropos of absolutely nothing, a question stolen from MetaFilter: 

Let's say, hypothetically, there is a MeFite who will turn 40 next year and is wondering what types of things they can do or avoid during the upcoming decade so on their 50th birthday they can look back and say, "Wow, what a great decade that was?" 

Actionable, specific ideas based on your own positive or unfortunate experiences are the most welcomed (see a doctor about ____ vs. "stay healthy"'; plan an overseas trip every single year vs. travel more, etc.). But all ideas are neat!

If you look through the thread, there's a lot about health and money. That kind of advice is happily welcome. Advice about what do to in your career would be helpful too. Readers?