Lots of practice. Read books about programming. I don't see how not wanting to go into programming as a career prevents you doing the things professional programmers do to enter the profession.
I learned how to maintain my motorcycles with no intention of becoming a mechanic, but I still had to read the service manuals and practice and ask for help.
Mostly time and mental capacity with already demanding job to be honest. I enjoy programming so much that I'd love to do it full-time, just not in a corporate.
I learned how to maintain my motorcycles with no intention of becoming a mechanic, but I still had to read the service manuals and practice and ask for help.