I really don't understand Specialists. Am I supposed to be toggling on the blank icons and put people there? Why do my cities get -Health [
] for Specialists? Are they unhappy because I have too few? Are they unhappy because I have too many? What is the deal?
How do I make specialists work? and what do I need to be doing with them?

How do I make specialists work? and what do I need to be doing with them?