Last Timer App

Density circuits involve:
* Setting a timeframe (10-15 minutes)
* Choosing 3-5 exercises
* Selecting rep ranges for those exercises
* Working until the timer sounds

Here's an example of a total body density circuit using a single kettlebell:
* Overhead Press × 8 reps/arm
* Goblet Squat x 8 reps
* Bent-Over Row x 8 reps/arm
* Kettlebell Swings × 8 reps