For many of the past 6 years, I actually had the freedom to do what I wanted and I naturally gravitated back to software development, so that's where I will spend most of my time - likely working on open-source libraries and utilities to help other developers.
I would, of course, structure my days differently and work fewer hours.
Other than that I'd also use the time to take courses about topics and learning skills outside of my typical areas of interest to build up a broader knowledge base.