Fantastic App
I really love this app. Ive used 5k, 10k, and now this one. I highly recommend it for someone trying to become a half marathon runner. I mainly run outside but have occasionally used it indoors too on the treadmill. The app still works on the treadmill however doesnt track distance. It only tracks your distance when outside.
SammieDoo about
Half Marathon Trainer: 21K Run