I use this lab when my students are learning about the muscles. It is a fun lab as long as your students don't get too rowdy.
I only do an activity for 2-3 minutes.
I explain to my students that this is NOT a contest- and there are no prizes that will be handed out for lasting the longest.
For the hurting heart portion you could use tennis balls, stress balls, or students could clench and un-clench their fists. (We used stress balls shaped like hearts)
We go through each question together after the activity. There is no answer key as most of the questions are your own opinion or what each individual student experiences. My students enjoy this lab and I hope yours do too!