I launched the first version of AvoToast, which focused on building customized meal plans for the users. You would sign up at $60/mo, get assigned a guide (which was just me to start), and taking into account your preferences, would create a custom meal plan and adjust it based on your feedback. I signed up 5 paying customers and quickly got overwhelmed with how much work creating the plans by hand were. Everyone's requirements were so different, there wasn't any scale, so I quickly pivoted to automatic meal plan generation for the next launch. I since dropped these users to free and they're hanging around waiting for the next launch.
I did this launch as part of Startup School 19.