Sir Ian McKellen believed he was immortal when he was younger.

The 76-year-old actor thought he would never die when he was in his younger years, but has started taking care of himself much more in recent years in a bid to ''hold off the inevitable''.

When asked how he keeps a youthful mind, he said: ''Keep working, keep moving, keep exercising, keep thinking, keep enjoying yourself.

''Maybe you'll hold off the inevitable. You won't, of course! I don't think that I'm immortal like I did when I was younger. 'Die? Me?' Yes Darling, we're all going to die.''

The 'Lord of the Rings' star admitted he does have personal limitations nowadays due to his advancing age, despite the fact he gets the roles he does due to his age.

He said: ''I am old. I've been a pensioner for over 10 years. So I have intimations of incapacity. As an actor you can call on that. I'm younger than Holmes in the film, and I feel younger. But it's not that difficult to know what I've got to look forward to.''

However, Sir Ian - who only found fame during middle age - said he has defied expectations with his career because of when his career really took off.

He told Time Out magazine: ''My generation was brought up to think there was a 'prime in life'. When your relationships were settled, your finances were in order, you knew what it was to be you.

''Well in my prime of life I became famous. It was surprising, but it's been very enjoyable. I get recognised, but not that often, and it's usually to say thank you. That's nice for any actor.''