Arnold Schwarzenegger thinks seeing a marriage counsellor is ''the biggest mistake'' he's ever made.

The 67-year-old actor, who separated from Maria Shriver in 2011 after 25 years of marriage after he confessed that he had fathered a son with their housekeeper Mildred Baena in 2007, considers their split to be his ''biggest failure,'' but claims their decision to seek therapy was a waste of time.

The 'Terminator Genisys' star, who attempted to save their relationship for the sake of their four children, Katherine, 25, Christina, 23, Patrick, 21, and Christopher, 17, said: ''I think that people should get help when they need help. We are not against that. But in my particular case, it was not helpful.

''It was the biggest mistake I've ever made because that guy was so full of s**t. He said more c**p and more nonsense...It was absolutely, totally counterproductive to our future relationship or to any hope to get together or anything like that. It was just nonsense talk. It was the biggest mistake. Maria talked me into it.

''I apologised to Maria. I apologised to the kids. And I tried to then move forward and say, you know, 'How do we make the best of it?'

''And, you know, it has worked out really so well with the help from Maria, with the help of the kids, but not because of the shrink or because of some psychiatrist.''

Arnold, who has yet to finalise his divorce from Maria, also has a close bond with his son with Mildred, Joseph, 17.

He told Howard Stern on his SiriusXM radio show: ''He is terrific and he totally understands the situation. It all has worked out really well.''