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1. Use sound cues. During the exercise, there should be a timer sound for the last 10sec of each exercise, that way people don’t have to stare at their phones to know when they should stop. You should also include a sound for the last 3sec of the rest phase.
2. Better prep. During the rest, include the instructions for the next exercise as well. I waste about 2-4seconds of reading how to do the exercise as the timer is going. Had I known the instructions beforehand, I’d feel better prepared to fully utilize every exercise-second to stretch. To be even more effective, use an audio clip to read the instructions out loud; some people don’t like reading, and/or do better with sound.
3. Include a jingle once the workout is completely done. It helps fulfill a sense of accomplishment.
Hope this helps!!