Automobile Exhaustion

It looks like Nathan ran out of fuel as he played with his cars this afternoon. I was walking around putting laundry away and he was just playing with his cars all by himself. I walked by the living room one last time to find him passed out in the middle of his road. Poor kid, he had his heart set on not taking a nap today. I tried three times to get him to take a nap in his bed before this, but each time he got up to play. When he woke up, he acted like nothing happened. He sat up and just started playing with cars again.