A method can include determining, by a head-mounted device based on first data received from a depth-sensing device included in the head-mounted device, that a first distance of the head-mounted device from a landmark is outside a completion range; outputting, based on the determination that the first distance of the head-mounted device from the landmark is outside the completion range from the landmark, an indication that a repetition has yet to be completed; determining, based on second data received from the depth-sensing device, that a second distance of head-mounted device from the landmark is within the completion range; and based on the determination that the second distance of the head-mounted device from the landmark is within the completion range, incrementing a repetition counter and outputting an indication that the repetition has been completed.