Just 2 little ideas:
I like very much that children do a little noise when I take them to collect something. The last little girl in my game say: "Weee!!" and, in French (write it: oui) that means "Yes!!". I adore that so, of course, she works a lot!!
Maybe they could say "No" some times because they want to do something else or when "nature is calling"?
And, the healers could work inside the hospital, at research for example, and become master-doctor faster...