What is your definition of objectivity? Objectivity in journalism would be telling the story as it is, with facts and real events. The journalist should not let their own feelings sway the way that they report on a story.
Why be objective? If a journalist is not objective when covering a story, that could question the reliability of it. A person may not be getting the whole truth, but rather their opinion.
How do you do it? A reporter should use facts only and let the readers convey their own opinion on the subject.