Walks through exporting Apple Health data from the Watch app and loading the XML into R with tidy tools. Demonstrates filtering and counting record types, isolating heart rate measurements, and converting units for analysis. Shows how to visualize trends, build a simple Shiny interface, and experiment with moving averages to explore your own heart rate patterns.

Explains the slowdown caused by RStudio's default Knit behavior spawning a fresh R session for every render. Describes building a console-based RMarkdown rendering addin that mirrors a TextMate workflow and keeps loaded packages in memory. Highlights the speed benefits along with the risk of hidden dependencies on the console environment and encourages periodic clean renders with Knit.