Just came across your idea through a Google alert and thought it was interesting! I have seen similar challenges used by hubbub health. https://www.hubbubhealth.com/
I work for hubbub, and the philosophy is definitely that a wellness program needs to be holistic and comprehensive to be effective. They use challenges to create a multitude of small healthy habits that grow into big changes in wellness.
Hope you don't think that I'm soliciting, I just thought you might want to know that this concept could certainly fit within existing wellness programs.