The One Flew Over the Cuckoo's Nest star is famed for his fiery temper and womanising ways, but admits ongoing professional help has been beneficial.
He tells British newspaper The Sun, "I have been in a lot of therapy over the years and have found it has helped. The therapist I use in Los Angeles says to me, 'Jack, you are one of the best patients I've ever had.' And I say, 'Why is that, Sidney?' He says. 'You usually know what your problem is, you do what I tell you and that's the end of the therapy.'"