def get_message(course_name, time_not_active):
    """
    Format the message that needs to be send.

    :param course_name: The name of the course.
    :type course_name: str
    :param time_not_active: Time that a student has not been active.
    :type time_not_active: int
    :return: Message to be send to users.
    :rtype: str
    """
    message = f'You have not viewed the course "{course_name}" in {time_not_active} day(s). ' \
              f'We advise you to stay active, so that you will not miss anything.'
    return message