New to Garmin for past 5mths, mostly running outside from distances between 5-16km; currently following Garmin coach for half marathon. Tonight I selected my planned run and treadmill feature and ran until my watch said I was done 6.74km avg 6:50pace. My treadmill however clocked me at 3.50miles (5.63km) so I selected calibrate & save; should it be that much off?? I feel like I cheated my plan