It is expected to help out your parents.
John's father asks John to mow the lawn as he's experiencing back pain.
John wants to respond to his father's request.
John tells his father that he'll do it right away.
John tells his father that he cannot mow the lawn as he himself is also nursing a recent injury.
John's father is relieved that his lawn will be taken care of while he rests.
John's father is stressed out because of the uncertainty of who will help him mow the lawn.