Years before filming began on Peter Jackson's The Hobbit: An Unexpected Journey, British star Sir Ian McKellen (known to many fans as Gandalf) began his own unexpected journey -- with prostate cancer.

"I've had prostate cancer for six or seven years," the 73-year-old actor revealed to the U.K.'s Mirror on Monday, Dec. 10. Fortunately, he added, his is a slow-growing kind that has yet to metastasize to other parts of his body.

"When you have got it, you monitor it and you have to be careful it doesn't spread," he explained. "But if it is contained in the prostate, it's no big deal."

"Many, many men die from it," he clarified, "but it's one of the cancers that is totally treatable, so I have 'waitful watching.' I am examined regularly, and it's just contained, it's not spreading. I've not had any treatment."

That said, the Lord of the Rings star admitted he initially feared the worst upon getting the diagnosis. "You do gulp when you hear the news," he confessed to the Mirror. "It's like when you go for an HIV test, you go, 'Arghhh, is this the end of the road?'"

"I have heard of people dying from prostate cancer, and they are the unlucky ones, the people who didn't know they had got it and it went on the rampage. But at my age, if it is diagnosed, it's not life-threatening."

In fact, despite the disease -- and a few other woes, including hearing problems and cataracts -- McKellen considers himself fairly fortunate, health-wise.

"I am absolutely fine, thank you very much!" the actor joked of his many maladies. "I am lucky -- I don't have aches and pains."

That's thanks in part to his active lifestyle. "I do Pilates regularly...and I recommend it to anyone of my age, because the temptation is not to exercise when you get older," the screen legend said.

"I always walk up the escalator on the [London subway] and I live in a house with a lot of stairs and that's good exercise," he added, noting that he was also blessed with good health care. "It is really, really wonderful that in your old age you are protected by specialists who understand your problems and sort them out for you. Well, isn't that what we all need?"

This article originally appeared on Usmagazine.com: Sir Ian McKellen Has Prostate Cancer