The importance of things changes with the passage of time. Some things have too much value today but become valueless tomorrow. Then what is the need to worry about a thing which lost its worth over time.
Overtime, human learning improves, exposure increases and maturity develops and, therefore, we give different values to the past things.
Sometimes, a problem has high value when a person considers that problem specific to him, however, once he learns that this is a common problem then the value of problem fades away.
Point: Many things which we worry about are not actually worth worrying.