As noted by MacRumors, Apple will host an Apple Watch activity challenge on International Dance Day, which is set to be celebrated on Friday, April 29.
The Activity Challenge will show up on the Apple Watch as a notification in the days leading up to the event. You can earn recording a Dance workout of 20 minutes or more on April 29. Record it with the Workout app or any app that adds workouts to Health.
International Dance Day is a global celebration of dance, created by the Dance Committee of the International Theatre Institute, the main partner for the performing arts of UNESCO. The event takes place every year on April 29 — the anniversary of the birth of Jean-Georges Noverre, the creator of modern ballet.