https://www.beeminder.com/lambdaloop/mustdo - doing 1 admin task per day (slowed down after 3 months, stopped after 6 months)
https://www.beeminder.com/lambdaloop/anki - reviewing some number of anki cards each day (lapsed after ~2 months, recovered but lapsed after 2 months again and stopped)
(goal was private when archived, but yah similar trajectory) - doing weekly reviews (lapsed after ~5 months)