I have focused on things like reading (read +40 books in 2017, up from 1-2 per year), wood working, sketching, running and skiing. To keep up my programming skills I have done a deep dive in new programming languages and fiddling with some side projects. It has been an incredible year for personal development and it has changed my perspective on what things are important in life (sitting in front of a screen 40-60 hours a week not being one of them). I highly recommend everyone to do this at least once in your career!