Dipping in to the structured workouts on Zwift. What a cool tool. I like how they have little drills built in like working on different cadences or emphasizing different parts of the pedal stroke. Erg mode is also nice to get a feel for what it feels like to hold steady power, something I'm not that good at yet.
I'm glad I didn't start out with this and just rode the bike for months, but I can only see it benefitting my outdoor rides.