Interns in training decided to take this senior doctor at his word. Too bad it totally backfired on him. They say aging is difficult — your body aches for no reason, you fall asleep in random places, and all the young people are talking about things you don't care about. Depending on the field you work in, however, seniority can be a great perk. If you're a professor, the more years you teach, the better your job security. And if you're a doctor, that's the exact path many professionals take to…