If you would like to use another music player when listening to music within the app, please follow these steps:

Android:

Note: The Couch-to-5K app recognizes all music tracks that are present on the phone/tablet's external storage (such as an SD-Card). Unfortunately, some music apps such as Google Play Music have their own private music storage and won't share the tracks with other apps.

1. Go to Settings
2. Uncheck Built-in Music Player under Music options
3. Select a workout
4. Press headphone icon at the top of the screen
5. Choose a music player from your phone

iPhone:

Music within Couch-to-5k automatically uses music from the iTunes Music app.  If you would like to listen to music from another player, you will need to stop the music from within Couch-to-5k and play your music in the background.