What is the most effective thing you did to improve your programming skills?

If I look back at my careers there are many ways I have tried to improve my coding skill : reading other's code, writing various programs, reading popular books, listening to many podcasts, watching screencasts and more.

My question is: What is the most effective thing you have done to improve your programming skills? What would you recommend to others that want to improve?

Expecting different answers here and no single "one size fits all" answer - What worked for different people?