The professor holds up a glass of water in class and asks students to guess its weight, which varies from 50g to 125g. He then asks what would happen if he held the glass up for longer periods, like an hour or day. The students note his arm would ache and possibly become numb. Though the glass's weight didn't change, the prolonged holding caused stress. The professor asks how to relieve the pain, and a student replies by putting the glass down. Similarly, we should "put down" life's problems each day to avoid stress and wake up fresh to handle challenges. The key message is to not dwell on problems but instead relax and reset each night.