My first thought was to create a die with an exercise for each face. By rolling it the exercise would have been selected randomly or the die could have been set with a specific face up for manual selection.

But because dice are often related to gambling it could have been interpreted as gambling with your happiness. That’s why I was looking for or comparing other objects.

I found out that a combination of a die and a spinning top is perfect. It is more related to fun and joy but it can still select the exercise randomly in a playful way.