My hobby is growing my pain medicine. Took me a couple years and a few thousand dollars to figure out what I was doing (I mean, I could spend the money buying it, or I could learn something and drop out of the system. That also leaves agorism/activism as a possibility, giving me an area of expertise.) Now it's a matter of spending as little time and especially money to produce for my meager needs, because selling is too risky and I don't want to be a caregiver (I can donate my overage for the indigent, though.)
Before I was diagnosed with my condition, I, like most software nerds, wasted my free time doing what I already do for a living (only what I wanted to do.). That, and I used to spend a lot of time bicycling.
I've considered writing growing software, but I figure most growers probably don't like the idea of keeping records.