First evidence of overtraining: I am sore as hell, and have been for weeks. I have to grab my pant leg in order to cross my leg to put on my shoes.
Second evidence of overtraining: I am losing motivation to workout, and to workout at the intensity I have been.
Third evidence: I feel like there have been some workouts where my heart rate was lower than what I thought it should have been for the perceived exertion. It was harder to raise my heart rate.