Tom Selleck quit 'Magnum, P.I.' because he craved a ''three-dimensional life''.

The 75-year-old actor starred as a private investigator on the crime drama show in the 1980s - but Tom ultimately walked away from the production because he wanted more from his life.

He explained: ''I quit 'Magnum', not because I didn't like it or I was tired of it. I was tired from it. And I wanted a three-dimensional life because I didn't have one.''

The hit TV show ran from 1980 until 1988, but Tom was never a fan Hollywood of the lifestyle.

He told PEOPLE magazine: ''I knew intellectually what it would mean in terms of being a public person, but until you've lived it, there's no way to understand it.

''I had a feeling of, 'I don't think I'm cut out for this.'''

Tom now stars in the police drama 'Blue Bloods' - and he feels the show has given him a healthy work-life balance.

The actor - who has been married to his second wife, Jillie Mack, since 1987 - conceded that he's ''enormously fortunate'' with how his career has developed.

He said: ''I'm proud of my work, I still love what I do, and I have my family. I've been enormously fortunate.''

In fact, in spite of his fame and success, Tom still regards himself as a ''fairly private person''.

The veteran star - who has Hannah, 31, and Kevin, 54 - added: ''I've always treasured the balance between work and time with my family. It's always about them.''

Meanwhile, Tom previously admitted that fans used to moan about the revealing shorts he wore on 'Magnum, P.I.'.

However, the actor defended the attire he wore on the show.

He explained: ''They were shorts like shorts are supposed to be. Now shorts are like pyjamas.''