That question seems easier to answer than it is. I started thinking about writing to use as supplemental income in my retirement. That’s the wrong mindset to have. I have discovered that when you start putting your thoughts and creativity into word, thinking about money will only allow you to focus on the financial impact you will have, and not on the real purpose of writing, which is to share what you have learned (good and bad) so others may benefit in some way, or give something of great enjoyment that fires the imagination.
I have discovered in myself a talent of writing for children. Not sure why, but it may just be that children and creativity go together like peanut butter and chocolate. Getting out of the stress of the corporate world has freed my thoughts to focus on the bigger picture of life, not the bottom dollar.