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 minutes, hours or days. The students note that his arm would begin to ache and could even become numb or require hospitalization. However, the weight of the glass did not change. The professor explains that life's problems are like the glass - they seem manageable at first but can paralyze us if dwelled upon. It is important to 'put the glass down' by not stressing over challenges when going to sleep, so that one feels fresh and able to handle issues the next day.