How do I have health bars displayed at all times in Starcraft II?

In this question, Davy8 mentions that it is possible to display health bars at all times, instead of having to use the alt button when you want to see them. My question is: how is this done?

It's an option under the menu -> gameplay settings. Let me look up the exact path for you real quick.

Edit: To get there, go Menu(F10) -> Options -> Gameplay Settings. There's a dropdown menu on the left for "Show Unit Status Bars".

To always show health, change it from "Normal" to "Selected" (to show health on only those units you've selected) or "Always" to show the health of every unit, ever.