A Life Of Its Own Meaning

(idiomatic) An independent existence with some characteristics of life.

Example: 1996, George Steiner, Tolstoy or Dostoevsky: An Essay in the Old Criticism, page 181
  Sartre rejects the notion that an imagined character possesses, in any rational sense, "a life of its own".
2002, John Seely Brown, Paul Duguid, The Social Life of Information, page 18
  […], information takes on not only a speed of its own, but a life of its own.
2003, Kristin Hunter Lattany, The Lakestown Rebellion, page 185
  A massive hangover with a life of its own kept Fess pinned to his bed most of Sunday.