How to simulate heart rate data in the simulator (version 8.1)

I'm new to building a Garmin App so my apologies for the naivety --

I'm trying to simply display heart rate data on the simulator, but I don't really understand how the simulator works. Going to Simulation -> Activity Data, there's a tab for Data Simulation. But when I start it, nothing happens. I'd love an explanation on how to activate the heart rate sensor in the simulator/how to activate the data simulation.